METHOD OF REDUCING THE VAPOUR PRESSURE OF ETHANOL-CONTAINING MOTOR FUELS FOR SPARK IGNITION COMBUSTION ENGINES

Abstract: Method of reducing the vapour pressure of a C3 to C12 hydrocarbon-based motor fuel mixture containing 0.1 to 20 % by volume of ethanol for conventional spark ignition internal combustion engines, wherein, in addition to an ethanol component (b) and a C3 to C12 hydrocarbon component (a), an oxygen-containing additive (c) selected from at least one of the following types of compounds: alcohol other than ethanol, ketone, ether, ester, hydroxy ketone, ketone ester, and a heterocyclic containing oxygen, is used in the fuel mixture in an amount of at least 0.05 by volume of the total fuel, is disclosed. A mixture of fuel grade ethanol (b) and oxygen-containing additive (c) usable in the method of the invention is also disclosed.

Description: METHOD OF REDUCING THE VAPOUR PRESSURE OF ETHANOL-CONTAINING MOTOR FUELS FOR SPARK IGNITION COMBUSTION ENGINES This invention relates to motor fuel for spark ignition internal combustion engines. More particularly the invention relates to a method for lowering the dry vapour pressure equivalent (DVPE) of a fuel composition including a hydrocarbon liquid and ethanol by using an oxygen-containing additive. The ethanol and DVPE adjusting components used to obtain the fuel composition are preferably derived from renewable raw materials. By means of the method of the invention motor fuels containing up to 20 % by volume of ethanol meeting standard requirements for spark ignition internal combustion engines operating with gasoline are obtainable. Background of the invention Gasoline is the major fuel for spark ignition internal combustion engines. The ex- tensive use of gasoline results in the pollution of the environment. The combustion of gasoline derived from crude oil or mineral gas disturbs the carbon dioxide balance in the atmosphere, and causes the greenhouse effect. Crude oil reserves are decreasing steadily with some countries already facing crude oil shortages. The growing concern for the protection of the environment, tighter requirements governing the content of harmful components in exhaust emissions, and crude oil shortages, force industry to develop urgently alternative fuels which burn more cleanly. The existing global inventory of vehicles and machinery operating with spark ignition internal combustion engines does not allow currently the complete elimination of gasoline as a motor fuel. The task of creating alternative fuels for internal combustion engines has existed for a long time and a large number of attempts have been made to use renewable resources for yielding motor fuel components. U.S. Patent No. 2,365,009, issued in 1944 describes the combination of C1-5, alcohols and C 3- 5 hydrocarbons for use as a fuel. In U.S. Patent No. 4,818,250 issued in 1989 it is proposed to use limonene obtained from citrus and other plants as a motor fuel, or as a component in blends with gasoline. In U.S. Patent No. 5,607,486 issued in 1997, there are disclosed novel engine fuel additives comprising terpenes, aliphatic hydrocarbons and lower alcohols. Currently tert-butyl ethers are widely used as components of gasolines. Motor fuels comprising tert-butyl ethers are described in U.S. Patent No. 4,468,233 issued in 1984. The major portion of these ethers is obtained from petroleum refining, but can equally be produced from renewable resources. Ethanol is a most promising product for use as a motor fuel component in mixtures with gasoline. Ethanol is obtained from the processing of renewable raw material, known generically as biomass, which, in turn, is derived from carbon dioxide under the influence of solar energy. The combustion of ethanol produces significantly less harmful substances in comparison to the combustion of gasoline. However, the use of a motor fuel principally containing ethanol requires specially designed engines. At the same time spark ig- nition internal combustion engines normally operating on gasoline can be operated with a motor fuel comprising a mixture of gasoline and not more than about 10 % by volume of ethanol. Such a mixture of gasoline and ethanol is presently sold in the United States as gasohol. Current European regulations concerning gasolines allow the addition to gasoline of up to 5 % by volume of ethanol. The major disadvantage of mixtures of ethanol and gasoline is that for mixtures containing up to about 20 % by volume of ethanol there is an increase in the dry vapour pressure equivalent as compared to that of the original gasoline. Figure 1 shows the behaviour of the dry vapour pressure equivalent (DVPE) as a function of the ethanol content of mixtures of ethanol and gasoline A92 summer, and gasoline A95 summer and winter at 37.8 °C. The gasolines known as A92 and A95 are standard gasolines purchased at gas stations in the United States and Sweden. Gasoline A92 originated in the United States and gasoline A95, in Sweden. The ethanol employed was fuel grade ethanol produced by Williams, USA. The DVPE of the mixtures was determined according to the standard ASTM D5191 method at the SGS laboratory in Stockholm, Sweden. For the range of concentrations by volume of ethanol between 5 and 10% which is of particular interest for use as a motor fuel for standard spark ignition engines, the data in Fig. 1 show that the DVPE of mixtures of gasoline and ethanol can exceed the DVPE of source gasoline by more than 10%. Since the commercial petroleum companies normally supply the market with gasoline already at the maximum al- lowed DVPE, which is strictly limited by current regulations, the addition of ethanol to such presently commercially available gasolines is not possible. It is known that the DVPE of mixtures of gasoline and ethanol can be adjusted. U.S. Patent No. 5,015,356 granted on May 14, 1991 proposes reformulating gasoline by removing both the volatile and non-volatile components from C 4 - C12 gasoline to yield either Cβ - C9 or Cβ - C10 intermediate gasoline. Such fuels are said to better facilitate the addition of alcohol over current gasoline because of their lower dry vapour pressure equivalent (DVPE). A disadvantage of this method of adjusting the DVPE of mixtures of gasoline and ethanol is that in order to obtain such a mixture it is necessary to produce a special reformulated gasoline, which adversely affects the supply chain and results in increased prices for the motor fuel. Also, such gasolines and their mixtures with ethanol have a higher flash point, which impairs their performance properties. It is known that some chemical components decrease DVPE when added to gasoline or to a mixture thereof with ethanol. For example, U.S. Patent No. 5,433,756 granted on July 18, 1995 discloses chemical clean-combustion-promoter compounds comprising, in addition to gasoline, ketones, nitro-paraffin and also alcohols other than ethanol. It is noted that the composition of the catalytic clean- combustion-promoter disclosed in the patent reduces the DVPE of gasoline fuel. Nothing is mentioned in this patent about the impact of the clean-combustion- promoter composition on the DVPE of mixtures of gasoline and ethanol. U.S. Patent No. 5,688,295 granted on November 18, 1997 provides a chemical com- pound as an additive to gasoline or as a fuel for standard gasoline engines. In accordance with the invention, an alcohol-based fuel additive is proposed. The fuel additive comprises from 20 - 70% alcohol, from 2.5 - 20% ketone and ether, from 0.03 - 20% aliphatic and silicon compounds, from 5 - 20% toluene and from 4 - 45% mineral spirits. The alcohol is methanol or ethanol. It is noted in the patent that the additive improves gasoline quality and specifically decreases DVPE. The disadvantages of this method of motor fuel DVPE adjustment are that there is a need for large quantities of the additive, namely, not less than 15 % by volume of the mixture; and the use of silicon compounds, which form silicon oxide upon combustion, results in increased engine wear. In W09743356 a method for lowering the vapour pressure of a hydrocarbon-alcohol blend by adding a co-solvent for the hydrocarbon and alcohol to the blend, is described. A spark ignition motor fuel composition is also disclosed, including a hydrocarbon component of C5 - Cs straight-chained or branched alkanes, essentially free of olefins, aromatics, benzene and sulphur, in which the hydrocarbon component has a minimum anti-knock index of 65, according to ASTM D2699 and D2700 and a maximum DVPE of 15 psi, according to ASTM D5191; a fuel grade alcohol; and a co-solvent for the hydrocarbon component and alcohol in which the components of the fuel composition are present in amounts selected to provide a motor fuel with a minimum anti-knock index of 87 and a maximum DVPE of 15 psi. The co-solvent used is biomass-derived 2-methyltetrahydrofuran (MTHF) and other het- erocyclical ethers such as pyrans and oxepans, MTHF being preferred. The disadvantages of this method for adjusting the dry vapour pressure equivalent of mixtures of hydrocarbon liquid and ethanol are the following: (1) It is necessary to use only hydrocarbon components C5 - Cs which are straight- chained or branched alkanes (i) free of such unsaturated compounds as olefins, benzene and other aromatics, (ii) free of sulphur and, as follows from the descrip- tion of the invention, (iii) the hydrocarbon component is a coal gas condensate or natural gas condensate; (2) It is necessary to use as a co-solvent for the hydrocarbon component and etha- nol only one particular class of chemical compounds containing oxygen; namely, ethers, including short-chained and heterocyclic ethers; (3) It is necessary to use a large quantity of ethanol in the fuel, not less than 25%; (4) It is necessary to use a large quantity of co-solvent, not less than 20%, of 2- methyltetrahydrofuran; and (5) It is required to modify the spark ignition internal combustion engine when operating with such fuel composition and, specifically, one must change the software of the on-board computer or replace the on-board computer itself. Accordingly, it is an object of the present invention to provide a method by which the above-mentioned drawbacks of the prior art can be overcome. It is a primary object of the invention to provide a method of reducing the vapour pressure of a C 3 to C12 hydrocarbon based fuel mixture containing up to 20% by volume of ethanol for conventional gasoline engines to not more than the vapour pressure of the C 3 to C12 hydrocarbon itself, or at least so as to meet the standard requirement on gasoline fuel. SUMMARY OF THE INVENTION The above-mentioned object of the present invention has been accomplished by means of the method of the preamble of claim 1 , characterised in that an oxygen- containing additive selected from at least one of the following types of compounds: alcohol other than ethanol, ketone, ether, ester, hydroxy-ketone, ketone ester, and a heterocyclic compound containing oxygen, is used in the fuel mixture in an amount of at least 0.05 % by volume of the overall fuel mixture. The present inventors have found that specific types of compounds exhibiting an oxygen-containing group surprisingly lower the vapour pressure of a gasoline- ethanol mixture. This effect can unexpectedly be further enhanced by means of specific Cβ - C12 hydrocarbon compounds. They have also found that the octane number of the resulting hydrocarbon based fuel mixture surprisingly can be maintained or even increased by using the oxygen- component of the present invention. According to the present method up to about 20 % by volume of fuel grade ethanol (b) can be used in the whole fuel compositions. The oxygen-containing additives (c) used can be obtained from renewable raw materials, and the hydrocarbon compo- nent (a) used can for example be any standard gasoline (which does not have to be reformulated) and can optionally contain aromatic fractions and sulphur, and also hydrocarbons obtained from renewable raw materials. By means of the method of the invention fuels for standard spark ignition internal combustion engines can be prepared, which fuels allow such engines to have the same maximum performance as when operated on standard gasoline currently on the market. A decrease in the level of toxic emissions in the exhaust and a decrease in the fuel consumption can also be obtained by using the method of the invention. According to one aspect of the invention, in addition to the dry vapour pressure equivalent (DVPE), the anti-knock index (octane number) can also be desirably controlled. It is yet another object to provide an additive mixture of fuel grade ethanol (b) and oxygen-containing additive (c), and optionally, the further component (d), being individual hydrocarbons of the C6-C12 fraction or their mixtures, which additive mixture subsequently can be used in the inventive method, i.e., added to the hydrocarbon component (a). The mixture of (b) and (c), and optionally (d), can also be used per se as a fuel for modified engines, i.e., not standard-type gasoline engines. The additive mixture can also be used for adjusting the octane number and/ or for lowering the vapour pressure of a high vapour pressure hydrocarbon component. Further objects and advantages of the present invention will be evident from the following detailed description, examples and dependent claims. Brief description of the drawings In Figure 1, the behaviour of the dry vapour pressure equivalent (DVPE) as a func- tion of the ethanol content of prior art mixtures of ethanol and gasoline is shown. In Figure 2, the behaviour of the dry vapour pressure equivalent (DVPE) of different fuels of the present invention as a function of the ethanol content thereof is shown. DETAILED DESCRIPTION OF THE PRESENT INVENTION The present method enables the use of C 3 - C12 hydrocarbon fractions as hydrocarbon component (a), including narrower ranges within this broader range, without restriction on the presence of saturated and unsaturated hydrocarbons, aromatics and sulphur. In particular, the hydrocarbon component can be a standard gasoline currently on the market, as well as other mixtures of hydrocarbons obtained in the refining of petroleum, off-gas of chemical-recovery coal carbonisation, natural gas and synthesis gas. Hydrocarbons obtained from renewable raw materials can also be included. The C3 - C12 fractions are usually prepared by fractional distillation or by blending various hydrocarbons. Importantly, and as previously mentioned, the component (a) can contain aromatics and sulphur, which are either co-produced or naturally found in the hydrocarbon component. According to the method of the present invention the DVPE can be reduced for fuel mixtures containing up to 20% volume of ethanol, calculated as pure ethanol. According to a preferred embodiment the vapour pressure of the hydrocarbon based ethanol-containing fuel mixture is reduced by 50% of the ethanol-induced vapour pressure increase, more preferably by 80%, and even more preferably the vapour pressure of the hydrocarbon based ethanol-containing fuel mixture is reduced to a vapour pressure corresponding to that of the hydrocarbon component alone, and/ or to the vapour pressure according to any standard requirement on commercially sold gasoline. As will be evident from the examples, the DVPE can be reduced if desired to a level even lower than that of the hydrocarbon component used. According to a most preferred embodiment the other properties of the fuel, such as for example the octane number, are kept within the required standard limits. This is accomplished by adding to the motor fuel composition at least one oxygen- containing organic compound (c) other than ethanol. The oxygen-containing organic compound enables adjustment of (i) the dry vapour pressure equivalent, (ii) the anti-knock index and other performance parameters of the motor fuel composition as well as (iii) the reduction of the fuel consumption and the reduction of toxic substances in the engine exhaust emissions. The oxygen-containing compound (c) has oxygen bound in at least any one of the following functional groups: O o I - C - O - H C - - c- o- c- - c- o c 0 H H 0 H 0 II 1 1 I 1 I 1 1 c - c 1 - c j - - c- c- - c- - o- c 1 t H O - H H \ / / \ C c c- o- ' N o^ i ^o^ Such functional groups are present, for example, in the following classes of organic compounds and which can be used in the present invention: alcohols, ketones, ethers, esters, hydroxy-ketones, ketone esters, and heterocyclics with oxygen- containing rings. The fuel additive can be derived from fossil-based sources or preferably from renewable sources such as biomass. The oxygen-containing fuel additive (c) can typically be an alcohol, other than ethanol. In general, aliphatic or alicyclic alcohols, both saturated and unsaturated, preferably alkanols, are employed. More preferably, alkanols of the general formula: R-OH where R is alkyl with 3 to 10 carbon atoms, most preferably 3 to 8 carbon atoms, such as propanol, isopropanol, n-butanol, isobutanol, tert-butanol, n- pentanol, isopentanol, tert-pentanol, 4-methyl-2-pentanol, diethylcarbinol, diiso- propylcarbinol, 2-ethylhexanol, 2,4,4-trimethylpentanol, 2,6-dimethyl-4-heptanol, linalool, 3,6-dimethyl-3-octanol, phenol, phenylmethanol, methylphenol, methylcy- clohexanol or similar alcohols, are employed, as well as their mixtures. The component (c) can also be an aliphatic or alicyclic ketone, both saturated and O unsaturated, of the general formula R — C — R ; where R and R' are the same or different and are each CI-CΘ hydrocarbons, which also can be cyclic, and are preferably C1-C4 hydrocarbons. Preferred ketones have a total (R+R') of 4 to 9 carbon atoms and include methylethyl ketone, methylpropyl ketone, diethylketone, meth- ylisobutyl ketone, 3-heptanone, 2-octanone, diisobutyl ketone, cyclohexanon, ace- tofenone, trimethylcycohexanone, or similar ketones, and mixtures thereof. The component (c) can also be an aliphatic or alicyclic ether, including both saturated and unsaturated ethers, of the general formula R-O-R', wherein R and R' are the same or different and are each a C1-C10 hydrocarbon group. In general, lower (CI-CΘ ) dialkyl ethers are preferred. The total number of carbon atoms in the ether is preferably from 6 to 10. Typical ethers include methyltertamyl ether, methyli- soamyl ether, ethylisobutyl ether, ethyltertbutyl ether, dibutyl ether, diisobutyl ether, diisoamyl ether, anisole, methylanisole, phenetole or similar ethers and mixtures thereof. The component (c) may further be an aliphatic or alicyclic ester, including saturated O II and unsaturated esters, of the general formula R — C — O — R ^ where R and R' are the same or different. R and R' are preferably hydrocarbon groups, more preferably alkyl groups and most preferably alkyl and phenyl having 1 to 6 carbon at- oms. Especially preferred is an ester where R is Cι-C 4 and R' is C4-C6. Typical esters are alkyl esters of alkanoic acids, including n-butylacetate, isobutylacetate, tert- butylacetate, isobutylpropionate, isobutylisobutyrate, n-amylacetate, isoamylace- tate, isoamylpropionate, methylbenzoate, phenylacetate, cyclohexylacetate, or similar esters and mixtures thereof. In general, it is preferred to employ an ester having from 5 to 8 carbon atoms. The additive (c) can simultaneously contain two oxygen- containing groups connected in the same molecule with different carbon atoms. The additive (c) can be a hydroxyketone. A preferred hydroxyketone has the general formula: H - 0 H O O 0 - H where R is hydrocarbyl, and Ri is hydrogen or hydrocarbyl, preferably lower alkyl, i.e. (C1-C4). In general, it is preferred to employ a ketol having 4 to 6 carbon atoms. Typical hydroxy-ketones include l-hydroxy-2-butanone, 3-hydroxy-2-butanone, 4- hydroxy-4-methyl-2-pentanone, or similar ketols or mixture thereof. In yet another embodiment the fuel additive (c) is a ketone ester, preferably of the general formula: H I R - C - C - C - O - R II I II O H O where R is hydrocarbyl, preferably lower alkyl, i.e. (Cι-C ). Typical ketone esters include methylacetoacetate, ethyl acetoacetate and tert-butyl acetoacetate. Preferably, such ketone esters have 6 to 8 carbon atoms. The additive (c) can also be a ring- oxygen- containing heterocyclic compound and, preferably, the oxygen-containing heterocycle has a C . Cs ring. More preferably, the heterocycle additive has a total of 5 to 8 carbon atoms. The additive can preferably have the formula (1) or (2) as follows: R R. 1 2 where R is hydrogen or hydrocarbyl, preferably -CH 3 , and Ri is -CH 3 , or -OH, or -CHsOH, or CH 3 CO 2 CH 2 -. A typical heterocyclic additive (c) is tetrahydrofurfuryl alcohol, tetrahydrofur- furylacetate, dimethyltetrahydrofurane, tetramethyltetrahydrofurane, methyltetra- hydropyrane, 4-methyl-4-oxytetrahydropyrane or similar heterocyclic additives, or mixtures thereof. Component (c) can also be a mixture of any of the compounds set out above from one or more of the above-mentioned different compound classes. Suitable fuel grade ethanol (b) to be used according to the present invention can readily be identified by the person skilled in the art. A suitable example of the ethanol component is ethanol containing 99.5% of the main substance. Any impurities included in the ethanol in an amount of at least 0.5 % by volume thereof and falling within the above-mentioned definition of component (c) should be taken into ac- count when determining the amount used of component (c). That is, such impurities must be included in an amount of at least 0.5% in the ethanol in order to be taken into account as a part of component (c) . Any water, if present in the ethanol, should preferably amount to no more than about 0.25 % by volume of the total fuel mixture, in order to meet the current standard requirements on fuels for gasoline engines. Thus, a denatured ethanol mixture as supplied to the market, containing about 92% of ethanol, hydrocarbons and by-products, can also be used as the ethanol component in the fuel composition according to the invention. Unless otherwise indicated all amounts are in % by volume based on the total volume of the motor fuel composition. Generally, the ethanol (b) is employed in amounts from 0.1% to 20%, typically from about 1% to 20 % by volume, preferably 3% to 15 % by volume and more preferably from about 5 to 10 % by volume. The oxygen- containing additive (c) is generally employed in amounts from 0.05% to about 15 % by volume, more generally from 0.1 to about 15 % by volume, preferably from about 3 - 10 % by volume and most preferably from about 5 to 10 % by volume. In general, the total volume of ethanol (b) and oxygen- containing additive (c) employed is from 0.15 to 25 % by volume, normally from about 0.5 to 25 % by volume, preferably from about 1 to 20 % by volume, more preferably from 3 to 15 % by volume, and most preferably from 5 to 15 % by volume. The ratio of ethanol (b) to oxygen-containing additive (c) in the motor fuel composition is thus generally from 1: 150 to 400: 1, and is more preferably from 1: 10 to 10: 1. The total oxygen content of motor fuel composition based on the ethanol and the oxygen additive, expressed in terms of weight % oxygen based on total weight of motor fuel composition, is preferably no greater than about 7 wt.%, more preferably no greater than about 5 wt.%. According to a preferred embodiment of the invention to obtain a motor fuel suit- able for the operation of a standard spark ignition internal combustion engine the aforesaid hydrocarbon component, ethanol, and additional oxygen-containing component are admixed to obtain the following properties of the resulting motor fuel composition: - density at 15°C and at normal atmospheric pressure of not less than 690 kg/m 3 ; - oxygen content, based on the amount of oxygen- containing components, of not more than 7% w/w of the motor fuel composition; - anti-knock index (octane number) of not lower than the anti-knock index (octane number) of the source hydrocarbon component and preferably for 0.5(RON+MON) of not less than 80; - dry vapour pressure equivalent (DVPE) essentially the same as the DVPE of the source hydrocarbon component and preferably from 20 kPa to 120 kPa; acid content of not more than 0.1% by weight HAc; pH from 5 to 9; - aromatic hydrocarbons content of not more than 40 % by volume, including benzene, and for benzene alone, not more than 1 % by volume; - limits of evaporation of the liquid at normal atmospheric pressure in % of source volume of the motor fuel composition: initial boiling point, min 20°C; volume (at 70°C, min) of the liquid 25% by evaporated volume; volume (at 100°C, min) of the liquid 50% by evaporated volume; volume (at 150°C, min) of the liquid 75% by evaporated volume; volume (at 190 C C, min) of the liquid 95% by evaporated volume; residue of distillation, max. 2% by volume; final boiling point, max. 205°C; - sulfur content of not more than 50mg/kg; - resins content of not more than 2mg/ 100ml. According to a preferred embodiment of the method of the invention the hydrocarbon component and ethanol should be added together, followed by the addition of the additional oxygen-containing compound or compounds to the mix. Afterwards, the resulting motor fuel composition should preferably be maintained at a temperature not lower than -35°C, for at least about one hour. It is a feature of this invention that the components of the motor fuel composition can be merely added to each other to form the desired composition. It is generally not required to agitate or otherwise provide any significant mixing to form the composition. According to a preferred embodiment of the invention to obtain a motor fuel composition suitable for operating a standard spark ignition internal combustion engine and with a minimal harmful impact on the environment, it is preferable to use oxy- gen- containing component(s) originating from renewable raw material(s). Optionally, a component (d) can be used for further lowering the vapour pressure of the fuel mixture of components (a) , (b) and (c) . An individual hydrocarbon selected from a C 6 - C12 fraction of aliphatic or alicyclic saturated and unsaturated hydro- carbons can be used as component (d). Preferably the hydrocarbon component (d) is selected from a Cβ-Cπ fraction. Suitable examples of (d) are benzene, toluene, xy- lene, ethylbenzene, isopropylbenzene, isopropyltoluene, diethylbenzene, isopropyl- xylene, tert-butylbenzene, tert-butyltoluene, tert-butylxylene, cyclooctadiene, cy- clooctotetraene, limonene, isooctane, isononane, isodecane, isooctene, myrcene, allocymene, tert-butylcyclohexane or similar hydrocarbons and mixtures hereof. Hydrocarbon component (d) can also be a fraction boiling at 100-200°C, obtained in the distillation of oil, bituminous coal resin, or synthesis gas processing products. As already mentioned the invention further relates to an additive mixture consisting of components (b) and (c) and, optionally also component (d), which subsequently can be added to the hydrocarbon component (a) and is also possible to use as such as a fuel for a modified spark ignition combustion engine. The additive mixture preferably has a ratio of ethanol (b) to additive (c) of 1: 150 to 200: 1 by volume. According to a preferred embodiment of the additive mixture, said mixture comprises the oxygen-containing component (c) in an amount from 0.5 up to 99.5 % by volume, and ethanol (b) in an amount from 0.5 up to 99.5 % by vol- ume, and component (d) comprising at least one Cβ - C12 hydrocarbon, more preferably C 8 -Cπ hydrocarbon, in an amount from 0 up to 99 % by volume, preferably from 0% up to 90%, more preferably from 0 up to 79,5%, and most preferably from 5 up to 77% of the additive mixture. The additive mixture preferably has a ratio of ethanol (b) to the sum of the other additive components (c)+(d) from 1:200 to 200: 1 by volume, more preferable a ratio of ethanol (b) to the sum of the components (c) + (d) is from 1: 10 to 10: 1 by volume. The octane number of the additive mixture can be established, and the mixture be used to adjust the octane number of the component (a) to a desired level by admix- ing a corresponding portion of the mixture (b), (c), (d) to component (a). As examples demonstrating the efficiency of the present invention the following motor fuel compositions are presented which are not to be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments of this invention. As will be obvious to the person skilled in the art, all the fuel compositions of the following Examples can of course also be obtained by first preparing an additive mixture of components (b) and (c), and optionally (d), which mixture thereafter can be added to the component (a), or vice versa. In this case a certain amount of mixing may be required. EXAMPLES To prepare the blended motor fuel the following was used as the components (b), (c), and (d): fuel grade ethanol purchased in Sweden at Sekab and in the USA from ADM Corp. and Williams; oxygen-containing compounds, individual unsubstituted hydrocarbons and mixtures hereof purchased in Germany from Merck and in Russia from Lu- koil. Naphtha, which is an oil straight run gasoline containing aliphatic and alicy- clic saturated and unsaturated hydrocarbons. Alkylate, which is a hydrocarbon fraction consisting almost completely of isoparaffine hydrocarbons obtained in alkylation of isobutene by butanol. Alkylbenzene, which is a mixture of aromatic hydrocarbons obtained in benzene alkylation. Mostly, technical grade alkylbenzene comprises ethylbenzene, propylbenzene, isopropyl- benzene, butylbenzene and others. All the testing of source gasolines and ethanol-containing motor fuels, including those comprising the components of this invention was performed employing the standard ASTM methods at the laboratory of SGS in Sweden and at Auto Research Laboratories, Inc., USA. The drivability testing was performed on a 1987 VOLVO 240 DL according to the standard test method EU2000 NEDC EC 98/69. The European 2000 (EU 2000) New European Driving Cycle (NEDC) standard test descriptions are identical to the standard EU/ECE Test Description and Driving Cycle (91/441 EEC resp. ECE-R 83/01 and 93/ 116 EEC). These standardised EU tests include city driving cycles and extra urban driving cycles and require that specific emission regulations be met. Exhaust emission analysis is conducted with a constant volume sampling procedure and utilises a flame ionisation detector for hydrocarbon determination. Exhaust Emission Directive 91/441 EEC (Phase I) provides specific CO, (HC + NO) and (PM) standards, while EU Fuel Consumption Directive 93/ 116 EEC (1996) implements consumption standards. The testing was performed on a 1987 Volvo 240 DL with a B230F, 4-cylinder, 2.32 litre engine (No. LG4F20-87) developing 83 kW at 90 revolutions /second and a torque of 185 Nm at 46 revolutions/ second. EXAMPLE 1 Example 1 demonstrates the possibility of reducing the dry vapour pressure equivalent of the ethanol-containing motor fuel for the cases when gasolines with dry vapour pressure equivalent according to ASTM D-5191 at a level of 90 kPa (about 13 psi) are used as a hydrocarbon base. To prepare the mixtures of this composition winter gasolines A92, A95, and A98, presently sold on the market and purchased in Sweden from Shell, Statoil, Q8OK and Preem, were used. Fig. 1 demonstrates the behaviour of the DVPE of the ethanol-containing motor fuel based on winter A95 gasoline. The ethanol-containing motor fuels based on winter A92 and A98 used in this example also demonstrate a similar behaviour. The source gasoline comprised aliphatic and alicyclic C4-C12 hydrocarbons, includ- ing both saturated and unsaturated ones. The winter A92 gasoline used had the following specification: DVPE = 89,0 kPa Anti-knock index 0.5(RON + MON)=87.7 The fuel 1-1 (not according to the invention) contained A92 winter gasoline and ethanol and had the following properties for different ethanol contents: A92 : Ethanol = 95 : 5 % by volume DVPE = 94.4 kPa 0.5(RON + MON) = 89.1 A92 : Ethanol = 90 : 10 % by volume DVPE = 94.0 kPa 0.5(RON + MON) = 90.2 The following different embodiments of the fuels 1-2 and 1-3 demonstrate the possibility of adjusting the dry vapor pressure equivalent (DVPE) of the ethanol- containing motor fuel based on winter A92 gasoline. The inventive fuel 1-2 contained A92 winter gasoline (a), ethanol (b) and oxygen- containing additives (c) and had the following properties for the various compositions: A92 : Ethanol : Isobutyl acetate = 88.5 : 4.5 : 7 % by volume DVPE = 89.0 kPa 0.5(RON + MON) = 89.9 A92 : Ethanol : Isoamyl acetate = 88 : 5 : 7 % by volume DVPE = 88.6 kPa 0.5(RON + MON) = 89.0 A92 : Ethanol : Diacetone alcohol = 88.5 : 4.5 : 7 % by volume DVPE = 89.0 kPa 0.5(RON + MON) = 89.65 A92 : Ethanol : Ethylacetoacetate = 90.5 : 2.5 : 7 % by volume DVPE = 89.0 kPa 0.5(RON + MON) = 87.8 A92 : Ethanol : Isoamylpropionate = 87.5 : 5.5 : 7 % by volume DVPE = 88.7 kPa 0.5(RON + MON) = 90.4 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel induced by the presence of ethanol to the level of the DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the winter gasoline is 90 kPa. A92 : Ethanol : 3-Heptanone = 85 : 7.5 : 7.5 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 89.9 A92 : Ethanol : 2,6-dimethyl-4-heptanol = 85 : 8.5 : 6.5 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 90.3 A92 : Ethanol : Diisobutyl ketone = 85 : 7.5 : 7.5 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 90.25 The inventive fuel 1-3 contained A92 winter gasoline (a), ethanol (b), oxygen- containing additives (c) and hydrocarbons C6-C12 (d), and had the following proper- ties for the various compositions: A92 : Ethanol : Isoamyl alcohol : Alkylate = 79 : 9 : 2 : 10 % by volume The boiling temperature of the alkylate is 100-130°C DVPE = 88.5 kPa 0.5(RON + MON) = 90.25 A92 : Ethanol : Isobutyl acetate : Naphtha = 80 : 5 : 5 : 10 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 88.7 kPa 0.5(RON + MON) = 88.6 A92 : Ethanol : Tert-butanol: Naphtha = 81 : 5 : 5 : 9 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 87.5 kPa 0.5(RON + MON) = 89.6 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel induced by the presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the winter gasoline is 90 kPa. A92 : Ethanol : Isoamyl alcohol : Benzene : Ethylbenzene : Diethyl benzene = 82.5 : 9.5 : 0.5 : 0.5 : 3 : 4 % by volume DVPE = 90 kPa 0.5(RON + MON) = 91.0 A92 : Ethanol : Isobutyl acetate : Toluene = 82.5 : 9.5 : 0.5 : 7.5 % by volume DVPE = 90 kPa 0.5(RON + MON) = 90.8 A92 : Ethanol : Isobutanol : Isoamyl alcohol : m-Xylene = 82.5 : 9.2 : 0.2 : 0.6 : 7.5 % by volume DVPE = 90 kPa 0.5(RON + MON) = 90.9 The following compositions 1-5 to 1-6 demonstrate the possibility of adjusting the dry vapor pressure equivalent (DVPE) of the ethanol-containing motor fuel based on winter A98 gasoline. The winter A98 gasoline had the following specification: DVPE = 89,5 kPa Anti-knock index 0.5(RON + MON)=92.35 The comparative fuel 1-4 contained A98 winter gasoline and ethanol and had the following properties for the various compositions: A98 : Ethanol = 95 : 5 % by volume DVPE = 95.0 kPa 0.5(RON + MON) = 92.85 A98 : Ethanol = 90 : 10 % by volume DVPE = 94.5 kPa 0.5(RON + MON) = 93.1 The fuel 1-5 contained A98 winter gasoline (a), ethanol (b), and oxygen- containing additives (c) and had the following properties for the various compositions: A98 : Ethanol : Isobutanol = 84 :9 : 7 % by volume DVPE = 88.5 kPa 0.5(RON + MON) = 93.0 A98 : Ethanol : Tert-butylacetate = 84 : 9 : 7 % by volume DVPE = 89.5 kPa 0.5(RON + MON) = 93.3 A98 : Ethanol : Benzyl alcohol = 85 : 7.5 : 7.5 % by volume DVPE = 89.5 kPa 0.5(RON + MON) = 93.05 A98 : Ethanol : Cyclohexanone = 85 : 7.5 : 7.5 % by volume DVPE = 88.0 kPa 0.5(RON + MON) = 92.9 A98 : Ethanol : Diethyl ketone = 85 : 7.5 : 7.5 % by volume DVPE = 89.0 kPa 0.5(RON + MON) = 92.85 A98 : Ethanol : Methylpropyl ketone = 85 : 7.5 : 7.5 % by volume DVPE = 89.5 kPa 0.5(RON + MON) = 93.0 A98 : Ethanol : Methylisobutyl ketone = 85 : 7.5 : 7.5 % by volume DVPE = 89.0 kPa 0.5(RON + MON) = 92.65 A98 : Ethanol : 3-heptanone = 85 : 7.5 : 7.5 % by volume DVPE = 89.5 kPa 0.5(RON + MON) = 92.0 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the winter gasoline is 90 kPa. A98 : Ethanol : Methylisobutyl ketone = 85 : 8 : 7 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 92.7 A98 : Ethanol : Cyclohexanone = 85 : 8.5 : 6.5 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 93.0 A98 : Ethanol : Methylphenol = 85 : 8 : 7 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 93.05 The fuel 1-6 contained A98 winter gasoline (a), ethanol (b), oxygen- containing additives (c), and C6-C12 hydrocarbons (d) and had the following properties for the various compositions: A98 : Ethanol : Isoamyl alcohol : Isooctane = 80 : 5 : 5 : 10 % by volume DVPE = 82.0 kPa 0.5(RON + MON) = 93.2 A98 : Ethanol : Isoamyl alcohol : m-Isopropyl toluene = 78.2 : 6.1 : 6.1 : 9.6 % by volume DVPE = 81.0 kPa 0.5(RON + MON) = 93.8 A98 : Ethanol : Isobutanol : Naphtha = 80 : 5 : 5 : 10 % by volume The boiling point of the naphtha is 100-200°C. DVPE = 82.5 kPa 0.5(RON + MON) = 92.35 A98 : Ethanol : Isobutanol : Naphtha : m-Isopropyl toluene = 80 : 5 : 5 : 5 : 5 % by volume The boiling point of the naphtha is 100-200°C. DVPE = 82.0 kPa 0.5(RON + MON) = 93.25 A98 : Ethanol : Tert-butyl acetate : Naphtha = 83 : 5 : 5 : 7 % by volume The boiling temperature of the naphtha is 100-200°C DVPE = 82.1 kPa 0.5(RON + MON) = 92.5 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the winter gasoline is 90 kPa. A98 : Ethanol : Isoamyl alcohol : Isooctane = 85 : 5 : 5 : 5 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 93.3 A98 : Ethanol : Isobutanol : Naphtha = 85 : 5 : 5 : 5 % by volume The boiling temperature of the naphtha is 100-200°C DVPE = 90.0 kPa 0.5(RON + MON) = 93.0 A98 : Ethanol : Isobutanol : Isopropyl xylene = 85 : 9.5 : 0.5 : 5 % by volume DVPE = 90 kPa 0.5(RON + MON) = 93.1 The motor fuel compositions below demonstrate that it might be necessary to reduce the excess DVPE of the motor fuel caused by presence of ethanol below the level of DVPE of the source gasoline. Normally, this is required when DVPE of the source gasoline is higher than the limits of the regulations in force for the corresponding gasoline. In this way, for example, it is possible to transform the winter grade gasoline into the summer grade gasoline. The DVPE level for the summer gasoline is 70 kPa. A98 : Ethanol : Isobutanol : Isooctane : Naphtha = 60 : 9.5 : 0.5 : 15 : 15 % by volume The boiling point of the naphtha is 100-200°C. DVPE = 70 kPa 0.5(RON + MON) = 92.85 A98 : Ethanol : Isobutanol : Alkylate : Naphtha = 60 : 9.5 : 0.5 : 15 : 15 % by volume The boiling point of the naphtha is 100-200°C. The boiling point of the alkylate is 100-130°C. DVPE = 70 kPa 0.5(RON + MON) = 92.6 A98 : Ethanol : Tert-butyl acetate : Naphtha = 60 : 9 : 3 : 28 % by volume The boiling point of the naphtha is 100-200°C. DVPE = 70 kPa 0.5(RON + MON) = 91.4 The following fuels 1-8, 1-9 and 1-10 demonstrate the possibility of adjusting the dry vapor pressure equivalent (DVPE) of the ethanol-containing motor fuel based on winter A95 gasoline. The winter A95 gasoline had the following specification: DVPE = 89.5 kPa Anti-knock index 0.5(RON + MON)= 90.1 Testing in accordance with the standard test method EU 2000 NEDC EC 98/69 as described above demonstrated the following results: CO (carbon monoxide) 2.13g/km; HC (hydrocarbons) 0.280g/km NOx (nitrogen oxides) - 0.265g/km C0 2 (carbon dioxide) 227.0g/km NMHC* 0.276g/km Fuel consumption, Fc 1/ 100km 9.84 * Non-methane hydrocarbons. The comparative fuel 1-7 contained A95 winter gasoline and ethanol, and had the following properties for the various compositions: A95 : Ethanol = 95 : 5 % by volume DVPE = 94.9 kPa 0.5(RON + MON) = 91.6 A95 : Ethanol = 90 : 10 % by volume (referred to as RFMl below) DVPE = 94.5 kPa 0.5 (RON + MON) = 92.4 The testing of the reference fuel mixture (RFMl) demonstrated the following results, as compared to the winter A95 gasoline: CO -15.0%; HC -7.3%; NOx +15.5%; C0 2 +2.4%; NMHC* -0.5%; Fuel consumption, F c , 1/ 100km +4.7% "-" represents a reduction in emission, while "+" represents an increase in emission. The inventive fuel 1-8 contained A95 winter gasoline (a), ethanol (b) and the oxygen- containing additives (c), and had the following properties for the various compositions: A95 : Ethanol : Diisoamyl ether = 86 : 8 : 6 % by volume DVPE = 87.5 kPa 0.5(RON + MON) = 90.6 A95 : Ethanol : Isobutyl acetate = 88 : 5 : 7 % by volume DVPE = 87.5 kPa 0.5(RON + MON) = 91.85 A95 : Ethanol : Isoamylpropionate = 88 : 5 : 7 % by volume DVPE = 87.0 kPa 0.5(RON + MON) = 91.35 A95 : Ethanol : Isoamylacetate = 88 : 5 : 7 % by volume DVPE = 87.5 kPa 0.5(RON + MON) = 91.25 A95 : Ethanol : 2-octanone = 88 : 5 : 7 % by volume DVPE = 87.0 kPa 0.5(RON + MON) = 90.5 A95 : Ethanol : Tetrahydrofurfuryl alcohol = 88 : 5 : 7 % by volume DVPE = 87.5 kPa 0.5(RON + MON) = 90.6 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the winter gasoline is 90 kPa. A95 : Ethanol : Diisoamyl ether = 87 : 9 : 4 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 91.0 A95 : Ethanol : Isoamyl acetate = 88 : 7 : 5 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 91.3 A95 : Ethanol : Tetrahydrofurfuryl alcohol = 88 : 7 : 5 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 90.8 The fuel 1-9 contained A95 winter gasoline (a), ethanol (b), the oxygen-containing additives (c), and Cβ-Ci2 hydrocarbons (d) and had the following properties for the various compositions: A95 : Ethanol : Isoamyl alcohol : Alkylate = 83.7 : 5 : 2 : 9.3 % by volume The boiling temperature of the alkylate is 100-130°C DVPE = 88.0 kPa 0.5(RON + MON) = 91.65 A95 : Ethanol : Isoamyl alcohol : Naphtha = 83.7 : 5 : 2 : 9.3% by vol. The boiling temperature of the naphtha is 100-200°C DVPE = 88.5 kPa 0.5(RON + MON) = 90.8 A95 : Ethanol : Isobutyl acetate : Alkylate = 81 : 5 : 5 : 9 % by volume The boiling temperature of the alkylate is 100-130°C DVPE = 87.0 kPa 0.5(RON + MON) = 92.0 A95 : Ethanol : Isobutyl acetate : Naphtha = 81 : 5 : 5 : 9 % by volume The boiling temperature of the naphtha is 100-200°C DVPE = 87.5 kPa 0.5(RON + MON) = 91.1 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the winter gasoline is 90 kPa. A95 : Ethanol : Isoamyl alcohol : Xylene = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 90.0 kPa 0.5(RON + MON) = 92.1 A95 : Ethanol : Isobutanol : Isoamyl alcohol : Naphtha = 80 : 9.2 : 0.2 : 0.6 : 10 % by volume The boiling temperature of the naphtha is 100-200°C DVPE = 90.0 kPa 0.5(RON + MON) = 91.0 A95 : Ethanol : Isobutanol : Isoamyl alcohol : Naphtha : Alkylate = 80 : 9.2 : 0.2 : 0.6 : 5 : 5 % by volume The boiling temperature of the naphtha is 100-200°C. The boiling point of the alkylate is 100-130°C. DVPE = 90.0 kPa 0.5(RON + MON) = 91.6 The motor fuel compositions below demonstrate that it might be necessary to reduce the excess DVPE of the motor fuel caused by presence of ethanol below the level of DVPE of the source gasoline. Normally, this is required when DVPE of the source gasoline is higher than the limits of the regulations in force for the corresponding gasoline. In this way, for example, it is possible to transform the winter grade gasoline into the summer grade gasoline. The DVPE level for the summer gasoline is 70 kPa. A95 : Ethanol : Isobutanol : Isoamyl alcohol : Naphtha : Isooctane = 60 : 9.2 : 0.2 : 0.6 : 15 : 15 % by volume The boiling temperature of the naphtha is 100-200°C. DVPE = 70.0 kPa 0.5(RON + MON) = 91.8 A95 : Ethanol : Tert-butyl acetate : Naphtha = 60 : 9 : 1 : 30 % by volume The boiling temperature of the naphtha is 100-200°C. DVPE = 70.0 kPa 0.5(RON + MON) = 90.4 The fuel 1-10 contains 75 % by volume A95 winter gasoline, 9.6 % by volume ethanol, 0.4 % by volume isobutyl alcohol, 4.5 % by volume m-isopropyl toluene and 10.5 % by volume naphtha with boiling temperature of 100-200°C. This fuel for- mulation demonstrates the possibility of decreasing the DVPE, increasing the octane number, decreasing the level of toxic emissions in the exhaust and decreasing the fuel consumption in comparison with the reference mixture of gasoline and ethanol (RFM 1). The motor fuel composition has the following properties: density at 15°C, according to ASTM D 4052 749.2 kg /m3; initial boiling point, according to ASTM D 86 29°C; vaporizable portion - 70° C 47.6 % by volume; vaporizable portion - 100°C 55.6 % by volume; vaporizable portion - 150°C 84.2 % by volume; vaporizable portion - 180°C 97.5 % by volume; final boiling point 194.9°C; evaporation residue 1.3 % by volume; loss by evaporation 1.6 % by volume; oxygen content, according to ASTM D4815 3.7%w/w; acidity, according to ASTM D1613 weight% HAc 0.004; pH, according to ASTM D1287 6.6; sulfur content, according to ASTM D 5453 18mg/kg; gum content, according to ASTM D381 1 mg/ 100ml; water content, according to ASTM D6304 0.03% w/w; aromatics, according to SS 155120, including benzene 30.2 % by volume; benzene alone, according to EN 238 0.7 % by volume; DVPE, according to ASTM D 5191 89.0kPa; anti-knock index 0.5(RON+MON), according to ASTM D 2699-86 and ASTM D 2700-86 92.6 The motor fuel formulation 1-10 was tested in accordance with the standard test method EU 2000 NEDC EC 98/69 and the following results, as compared to winter A95 gasoline, were obtained: CO -21%; HC -9%; NOx +12.8%; C02 +2.38%; NMHC -6.4%; Fuel consumption, Fc 1/ 100km +3.2% The fuel formulations 1-1 to 1-10 showed reduced DVPE over the tested ethanol- containing motor fuels based on summer grade gasoline. Similar results are obtained when other oxygen-containing compounds of this invention are substituted for the additives of the examples 1-1 to 1-10. To prepare the above fuel formulations 1-1 to 1-10 of this motor fuel composition, initially gasoline was mixed with ethanol and the corresponding oxygen-containing additive was added to the fuel mixture. The motor fuel composition obtained was then allowed to stand before testing between 1 and 24 hours at a temperature not lower than -35°C. All the above formulations were prepared without the use of any mixing devices. It was established the possibility of employing an additive mixture of the oxygen- containing additive other than ethanol (c) and ethanol (b) for formulating the ethanol-containing motor fuels for standard internal combustion spark ignition engines meeting standard requirements for gasolines, both regarding vapour pressure and anti-knock stability. The fuel compositions below demonstrate such a possibility. An mixture comprising 50% of ethanol and 50% of isoamyl alcohol was in different proportions mixed with winter grade gasolines, the dry vapour pressure equivalent (DVPE) of which does not exceed 90 kPa. All the resulting mixtures had the DVPE not higher than that required by the regulations for winter gasoline, namely 90 kPa. A92 : Ethanol : Isoamyl alcohol = 87 : 6.5 : 6.5 % by volume DVPE = 89.0 kPa 0.5(RON + MON) = 90.15 A95 : Ethanol : Isoamyl alcohol = 86 : 7.0 : 7.0 % by volume DVPE = 89.3 kPa 0.5(RON + MON) = 92.5 A98 : Ethanol : Isoamyl alcohol = 85 : 7.5 : 7.5 % by volume DVPE = 86.5 kPa 0.5(RON + MON) = 92.9 Figure 2 shows the behavior of the dry vapour pressure equivalent (DVPE) as a function of the ethanol content when admixing the additive mixture 2 comprising 33.3% of ethanol and 66.7% of tert-pentanol with A95 winter gasoline. Figure 2 demonstrates that varying the ethanol content in gasoline within the range from 0 to 11% does not induce an increase of the vapour pressure for these compositions higher than the requirements of the standards for DVPE of the winter grade gasolines, which is 90 kPa. Similar DVPE behaviour was observed for A92 and A98 winter gasoline mixed with an additive mixture comprising 33.3 % by volume of ethanol and 66.7 % by volume of tert-pentanol. The effect of the reduction of the vapour pressure of the ethanol-containing gasolines while increasing the ethanol content in the resulting composition from 0 to 11 % by volume was also observed when part of the oxygen-containing additive was replaced by C 6 -Ci2 hydrocarbons (component (d)). The compositions below demonstrate the effect achieved by means of the invention. An additive mixture comprising 40 % by volume of ethanol, 10 % by volume of isobutanol and 50 % by volume of isopropyltoluene was mixed with winter gasoline with DVPE not higher than 90 kPa. The various compositions obtained had the following properties: A92 : Ethanol: Isobutanol : Isopropyltoluene = 85 : 6 : 1.5 : 7.5 % by volume DVPE = 84.9 kPa 0.5(RON + MON) = 93.9 A95 : Ethanol: Isobutanol : Isopropyltoluene = 80 : 8 : 2 : 10 % by volume DVPE = 84.0 kPa 0.5(RON + MON) = 94.1 A98 : Ethanol: Isobutanol : Isopropyltoluene = 86 : 5.6 : 1.4 : 7 % by volume DVPE = 85.5 kPa 0.5(RON + MON) = 93.8 Similar results were obtained when other oxygen-containing compounds and also C6-C12 hydrocarbons of the present invention were used in the ratio of the invention to prepare the additive mixture, which was then used for preparation of the ethanol-containing gasolines. These gasolines entirely meet the requirements for the motor fuels used in the standard spark ignition engines. EXAMPLE 2 Example 2 demonstrates the possibility of reducing the dry vapour pressure equivalent of the ethanol-containing motor fuel for the cases when gasolines with a dry vapour pressure equivalent according to ASTM D-5191 at a level of 70 kPa (about 10 psi) are used as a hydrocarbon base. To prepare the mixtures of this composition summer gasolines A92, A95 and A98 presently sold on the market and purchased in Sweden from Shell, Statoil, Q8OK, and Preem, were used. The source gasoline comprised aliphatic and alicyclic C4-C12 hydrocarbons, including saturated and unsaturated ones. Figure 1 shows the behaviour of the DVPE of the ethanol-containing motor fuel based on summer A95 gasoline. The ethanol-containing motor fuels based on winter A 92 and A98 gasolines, respectively, demonstrated similar behaviour. The following fuels 2-2 and 2-3 demonstrate the possibility of adjusting the dry vapour pressure equivalent (DVPE) of the ethanol-containing motor fuel based on summer A92 gasoline. The summer A92 gasoline had the following properties: DVPE = 70,0 kPa Anti-knock index 0.5(RON + MON)=87.5 The comparative fuel 2- 1 contained A92 summer gasoline and ethanol, and had the following properties for the various compositions: A92 : Ethanol = 95 : 5 % by volume DVPE = 77.0 kPa 0.5(RON + MON) = 89.3 A92 : Ethanol = 90 : 10 % by volume DVPE = 76.5 kPa 0.5(RON + MON) = 90.5 The fuel 2-2 contained A92 summer gasoline (a), ethanol (b), and the oxygen- containing additives (c) and had the following properties for the various compositions: A92 : Ethanol : Isoamyl alcohol = 85 : 6.5 : 6.5 % by volume DVPE = 69.8 kPa 0.5(RON + MON) = 90.3 A92 : Ethanol : Isobutanol = 80 : 10 : 10 % by volume DVPE = 67.5 kPa 0.5(RON + MON) = 90.8 A92 : Ethanol : Diethylcarbinol = 85 : 6.5 : 6.5 % by volume DVPE = 69.6 kPa 0.5(RON + MON) = 90.5 A92 : Ethanol : Diisobutyl ketone = 85.5 : 7.5 : 7 % by volume DVPE = 69.0 kPa 0.5(RON + MON) = 90.0 A92 : Ethanol : Diisobutyl ethter = 85 : 8 : 7 % by volume DVPE = 68.9 kPa 0.5(RON + MON) = 90.1 A92 : Ethanol : Di-n-butyl ester = 85 : 8 : 7 % by volume DVPE = 68.5 kPa 0.5(RON + MON) = 88.5 A92 : Ethanol : Isobutylacetate = 88 : 5 : 7 % by volume DVPE = 69.5 kPa 0.5(RON + MON) = 89.5 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the summer gasoline is 70 kPa. A92 : Ethanol : Isobutanol = 87.5 : 10 : 7.5 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 90.6 A92 : Ethanol : Di-n-butyl ether = 85 : 9 : 6 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 89.2 A92 : Ethanol : Diisobutyl ketone = 85 : 8 : ' 7 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 90.4 The fuel 2-3 contained A92 summer gasoline (a), ethanol (b), the oxygen- containing additives (c), and C6-C12 hydrocarbons (d) and had the following properties for the various compositions: A92 : Ethanol : Methylethyl ketone : Isooctane = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 69.0 kPa 0.5(RON + MON) = 91.0 A92 : Ethanol : Isobutanol : Isooctane = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 69.0 kPa 0.5(RON + MON) = 91.1 A92 : Ethanol : Isobutanol : Isononane = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 68.8 kPa 0.5(RON + MON) = 91.0 A92 : Ethanol : Isobutanol : Isodecane = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 68.5 kPa 0.5(RON + MON) = 90.8 A92 : Ethanol : Isobutanol : Isooctene = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 68.9 kPa 0.5(RON + MON) = 91.2 A92 : Ethanol : Isobutanol : Toluene = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 68.5 kPa 0.5(RON + MON) = 91.4 A92 : Ethanol : Isobutanol : Naphtha = 80 : 9.5 : 0.5 : 10 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 67.5 kPa 0.5(RON + MON) = 90.4 A92 : Ethanol : Isobutanol : Naphtha : Toluene = 80 : 9.5 : 0.5 : 5 : 5 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 67.5 kPa 0.5(RON + MON) = 90.9 A92 : Ethanol : Isobutanol : Naphtha : Isopropyltoluene = 80 : 9.5 : 0.5 : 5 : 5 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 67.5 kPa 0.5(RON + MON) = 91.2 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the summer gasoline is 70 kPa. A92 : Ethanol : Isobutanol : Isodecane = 82.5 : 9.5 : 0.5 : 7.5 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 90.85 A92 : Ethanol : Isobutanol : Tert-butylbenzene = 82.5 : 9.5 : 0.5 : 7.5 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 91.5 A92 : Ethanol : Isobutanol : Isoamyl alcohol : Naphtha : Tert-butyltoluene = 82.5 : 9.2 : 0.2 : 0.6 : 5 : 2.5 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 91.1 The following fuels 2-5 and 2-6 demonstrate the possibility of adjusting the dry vapour pressure equivalent (DVPE) of the ethanol-containing motor fuel based on summer A98 gasoline. The summer A98 gasoline had the following specification: DVPE = 69,5 kPa Anti-knock index 0.5(RON + MON)=92.5 The comparative fuel 2-4 contained A98 summer gasoline and ethanol, and had the following properties for the various compositions: A98 : Ethanol = 95 : 5 % by volume DVPE = 76.5 kPa 0.5(RON + MON) = 93.3 A98 : Ethanol = 90 : 10 % by volume DVPE = 76.0 kPa 0.5(RON + MON) = 93.7 The fuel 2-5 contained A98 summer gasoline (a), ethanol (b) and the oxygen- containing additives (c), and had the following properties for the various compositions: A98 : Ethanol : Isobutanol = 85 : 7.5 : 7.5 % by volume DVPE = 69.5 kPa 0.5(RON + MON) = 93.5 A98 : Ethanol : Diisobutyl ketone = 83 : 9.5 : 7.5 % by volume DVPE = 69.0 kPa 0.5(RON + MON) = 93.9 A98 : Ethanol : Isobutyl acetate = 88 : 5 : 7 % by volume DVPE = 69.5 kPa 0.5(RON + MON) = 93.4 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by the presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the summer gasoline is 70 kPa. A98 : Ethanol : Isobutanol = 85 : 8 : 7 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 93.7 A98 : Ethanol : Tert-pentanol = 90 : 5 : 5 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 93.8 The fuel 2-6 contained A98 summer gasoline (a), ethanol (b), the oxygen-containing additives (c), and C 6 -Ci2 hydrocarbons (d) and had the following properties for the various compositions: A98 : Ethanol : Isobutanol : Isooctane = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 69.0 kPa 0.5(RON + MON) = 93.7 A98 : Ethanol : Isopropanol : Alkylbenzene = 80 : 5 : 5 : 10 % by volume DVPE = 68.5 kPa 0.5(RON + MON) = 94.0 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by the presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the summer gasoline is 70 kPa. A98 : Ethanol : Isobutanol : Isooctane = 81.5 : 9.5 : 0.5 : 8.5 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 93.5 A98 : Ethanol : Tert-butanol : Limonene = 86 : 7 : 4 : 4 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 93.6 The following fuels 2-8 to 2-10 demonstrate the possibility of adjusting the dry vapour pressure equivalent (DVPE) of the ethanol-containing motor fuel based on summer A95 gasoline. The summer A95 gasoline had the following specification: DVPE = 68,5 kPa Anti-knock index 0.5(RON + MON) = 89.8 The testing performed as above demonstrated for the summer A95 gasoline the following results: CO (carbon monoxide) 2.198g/km HC (hydrocarbons) 0.245g/km NOx (nitrogen oxides) 0.252g/km C0 2 (carbon dioxide) 230.0g/km NMHC* 0.238g/km Fuel consumption, F c 1/ 100km 9.95 * Non-methane hydrocarbons. The comparative fuel 2-7 contained A95 summer gasoline and ethanol, and had the following properties for the various compositions: A95 : Ethanol = 95% : 5 % by volume DVPE = 75.5 kPa 0.5(RON + MON) = 90.9 A95 : Ethanol = 90% : 10 % by volume (also referred to as RFM2 below) DVPE = 75.0 kPa 0.5(RON + MON) = 92.25 The testing of the reference fuel mixture (RFM 2) demonstrated the following results, as compared to summer A95 gasoline: CO -9.1%; HC -4.5%; NOx +7.3%; C0 2 +4.0%; NMHC* -4.4%; Fuel consumption, F, 1/ 100km +3.6% "-" represents a reduction in emission, while "+" represents an increase in emission The fuel 2-8 contained A95 summer gasoline and the oxygen-containing additives and had the following properties for the various compositions: A95 : Ethanol : Isoamyl alcohol = 85 : 7.5 : 7.5 % by volume DVPE = 68.5 kPa 0.5(RON + MON) = 92.2 A95 : Ethanol : Diisoamyl ether = 86 : 8 : 6 % by volume DVPE = 66.5 kPa 0.5(RON + MON) = 90.2 A95 : Ethanol : Isobutylacetate = 88 : 5 : 7 % by volume DVPE = 67.0 kPa 0.5(RON + MON) = 92.0 A95 : Ethanol : Tert-butanol = 88 : 5 : 7 % by volume DVPE = 68.4 kPa 0.5(RON + ' MON) = 92.6 A95 : Ethanol : Tert-pentanol = 90 : 5 : 5 % by volume DVPE = 68.5 kPa 0.5(RON + MON) = 92.2 A95 : Ethanol : Isopropanol = 80 : 10 : 10 % by volume DVPE = 68.5 kPa 0.5(RON + MON) = 92.8 A95 : Ethanol : 4-methyl-2-pentanol = 85 : 8 : 7 % by volume DVPE = 66.0 kPa 0.5(RON + MON) = 91.0 A95 : Ethanol : Diethyl ketone = 85 : 8 : 7 % by volume DVPE = 68.0 kPa 0.5(RON + MON) = 92.2 A95 : Ethanol : Trimethylcyclohexanone = 85 : 8 : 7 % by volume DVPE = 67.0 kPa 0.5(RON + MON) = 91.8 A95 : Ethanol : Methyltertamyl ether = 80 : 8 : 12 % by volume DVPE = 68.0 kPa 0.5(RON + MON) = 93.8 A95 : Ethanol : n-Butylacetate = 87 : 6.5 : 6.5 % by volume DVPE = 68.0 kPa 0.5(RON + MON) = 90.1 A95 : Ethanol : Isobutylisobutyrate = 90 : 5 : 5 % by volume DVPE = 68.5 kPa 0.5(RON + MON) = 90.0 A95 : Ethanol : Methylacetoacetate = 85 : 7 : 8 % by volume DVPE = 68.5 kPa 0.5(RON + MON) = 89.9 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by the presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the summer gasoline is 70 kPa. A95 : Ethanol : 4-methyl-2-pentanol = 85 : 10 : 5 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 91.6 A95 : Ethanol : Isobutylisobutyrate = 90 : 6 : 4 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 90.5 The fuel 2-9 contained A95 summer gasoline (a), ethanol (b), the oxygen-containing additives (c), and Cβ-Ci2 hydrocarbons (d) and had the following properties for the various compositions: A95 : Ethanol : Tert-pentanol: Alkylbenzene = 80 : 7 : 4 : 9 % by volume DVPE = 67.5 kPa 0.5(RON + MON) = 93.6 A95 : Ethanol : Tert-butanol: Alkylbenzene = 80 : 7 : 4 : 9 % by volume DVPE = 68.0 kPa 0.5(RON + MON) = 93.8 A95 : Ethanol : Propanol : Xylene = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 68.0 kPa 0.5(RON + MON) = 93.1 A95 : Ethanol : Diethylketone : Xylene = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 68.0 kPa 0.5(RON + MON) = 93.2 A95 : Ethanol : Isobutanol : Naphtha : Isopropyltoluene = 80 : 9.5 : 0.5 : 5 : 5 % by volume The boiling temperature for the naphtha is 100-170°C DVPE = 68.0 kPa 0.5(RON + MON) = 92.4 A95 : Ethanol : Isobutanol : Naphtha : Alkylate = 80 : 9.5 : 0.5 : 5 : 5 % by volume The boiling temperature for the naphtha is 100-170°C The boiling temperature for the alkylate is 100-130°C DVPE = 68.5 kPa 0.5(RON + MON) = 92.2 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by the presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the summer gasoline is 70 kPa. A95 : Ethanol : Isobutanol : Isoamyl alcohol : Xylene = 82.5 : 9.2 : 0.2 : 0.6 : 7.5 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 93.0 A95 : Ethanol : Isobutanol : Isoamyl alcohol : Cyclooctadiene = 82.5 : 9.2 : 0.2 : 0.6 : 7.5 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 92.1 The fuel formulation 2-10 contained 81.5% by volume of A95 summer gasoline, 8.5% by volume of m-isopropyltoluene, 9.2% by volume of ethanol, and 0.8% by volume of isoamyl alcohol. Formulation 2-10 was tested to demonstrate how the inventive composition maintained the dry vapour pressure equivalent at a same level as the source gasoline while increasing the octane number, while decreasing the level of toxic emissions in the exhaust and decreasing the fuel consumption in comparison with the mixture RFM 2 of gasoline and ethanol. Formulation 2-10 had the following specific properties: density at 15°C, according to ASTM D4052 754.1kg /m3; initial boiling point, according to ASTM D 86 26.6°C; vaporisable portion - 70°C 45.2 % by volume; vaporisable portion - 100°C 56.4 % by volume; vaporisable portion - 150°C 88.8 % by volume; vaporisable portion - 180°C 97.6 % by volume; final boiling point 186.3°C; evaporation residue 1.6 % by volume; loss by evaporation 0.1 % by volume; oxygen content, according to ASTM D4815 3.56% w/w; acidity, according to ASTM D1613 weight% HAc 0.007; pH, according to ASTM D1287 8.9; sulfur content, according to ASTM D 5453 16mg/kg; gum content, according to ASTM D381 < lmg/ 100ml; water content, according to ASTM D6304 0.12% w/w; aromatics, according to SS 155120, including benzene 30.3 % by volume; benzene alone, according to EN 238 0.8 % by volume; DVPE, according to ASTM D 5191 68.5kPa; anti-knock index 0.5(RON+MON), according to ASTM D 2699-86 and ASTM D 2700-86 92.7 The motor fuel Formulation 2-10 was tested in accordance with test method EU 2000 NEDC EC 98/69 as above and gave the following results in comparison (+) or (-)% with the results for the source A95 summer gasoline: CO -0.18%o HC -8.5%; NOx +5.3%; C0 2 +2.8%; NMHC -9%; Fuel consumption, Fc, 1/ 100km +3.1% The fuel formulations 2-1 to 2- 10 showed reduced DVPE over the tested ethanol- containing motor fuels based on summer grade gasoline. Similar results are obtained when other oxygen-containing additives of the invention are substituted for the additives of the examples 2-1 to 2-10. To prepare all the above fuel formulations 2-1 to 2-10 of this motor fuel composition, initially gasoline was mixed with ethanol, to which mixture was then added the corresponding oxygen-containing additive. The motor fuel composition obtained was then allowed to stand before testing between 1 and 24 hours at a temperature not lower than -35°C. All the above formulations were prepared without the use of any mixing devices. The use of an additive mixture comprising ethanol and oxygen-containing com- pounds other than ethanol for preparation of the ethanol-containing gasolines was accomplished with summer grade gasolines. The fuel compositions below demonstrate the possibility of obtaining the ethanol-containing gasolines to meet standard requirements for summer grade gasolines, including vapour pressure of not higher than 70 kPa. Figure 2 shows the behaviour of the dry vapour pressure equivalent (DVPE) as a function of the ethanol content when mixing summer A95 gasoline with the additive mixture 3 comprising 35 % by volume of ethanol , 5 % by volume of isoamyl alcohol, and 60 % by volume of naphtha boiling at temperatures between 100-170°C. Figure 2 demonstrates that varying the ethanol content in gasoline within the range from 0 to 20% does not induce an increase of the vapour pressure for these compositions higher than the requirements of the standards for DVPE of the summer grade gasolines, which is 70 kPa. Similar DVPE behaviour was observed for A92 and A98 summer gasoline mixed with an additive mixture comprising 35 % by volume of ethanol, 5 % by volume of isoamyl alcohol, and 60 % by volume of naphtha boiling at 100-170°C. The ratio between ethanol and the oxygen-containing compound other than ethanol in the additive mixture, which is used for preparation of the ethanol-containing gasolines, is of substantial importance. The ratio between the components of the additive established by the present invention enables to adjust the vapour pressure of the ethanol-containing gasolines over a wide range. The compositions below demonstrate the possibility of employing the additive mixtures with both high and low ethanol content. An additive mixture comprising 92 % by volume of ethanol, 6 % by volume of isoamylalcohol, and 2 % by volume of isobutanol was mixed with summer grade gasoline. The compositions obtained had the following properties: A92 : Ethanol : Isoamyl alcohol : Isobutanol = 80 : 18.4 : 1.2 : 0.4 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 90.3 A95 : Ethanol : Isoamyl alcohol : Isobutanol = 82 : 16.56 : 1.08 : 0.36 % by volume DVPE = 69.9 kPa 0.5(RON + MON) = 92.6 A98 : Ethanol : Isoamyl alcohol : Isobutanol = 78 : 20.24 : 1.32 : 0.44 % by volume DVPE = 70.0 kPa 0.5(RON + MON) = 94.5 An additive mixture comprising 25 % by volume of ethanol, 60 % by volume of isoamyl alcohol, and 15 % by volume of isobutanol was mixed with summer grade ga- soline. The compositions obtained had the following properties: A92 : Ethanol : Isoamyl alcohol : Isobutanol = 80 : 5 : 12 : 3 % by volume DVPE = 66.0 kPa 0.5(RON + MON) = 88.6 A95 : Ethanol : Isoamyl alcohol : Isobutanol = 84 : 4 : 9.6 : 2.4 % by volume DVPE = 65.5 kPa 0.5(RON + MON) = 91.3 A98 : Ethanol : Isoamyl alcohol : Isobutanol = 86 : 3.5 : 8.4 : 2.1 % by volume DVPE = 65.0 kPa 0.5(RON + MON) = 93.0 Similar results were obtained when other oxygen-containing compounds (c) and also C6-Cι 2 hydrocarbons (d) of this invention were used in the ratio established by this invention to prepare the additive mixture, which was then used for preparation of the ethanol-containing gasolines. These gasolines entirely meet the requirements for the motor fuels used in the standard spark ignition engines. Moreover, the additive mixture comprising ethanol and the oxygen- containing compound of this invention other than ethanol with the ratio of the present invention can be used as an independent motor fuel for the engines adapted for operation on ethanol. EXAMPLE 3 Example 3 demonstrates the possibility of reducing the dry vapour pressure equivalent of the ethanol-containing motor fuel for the cases when gasolines with dry vapour pressure equivalent according to ASTM D-5191 at a level of 48 kPa (about 7 pSi) are used as the hydrocarbon base. To prepare the mixtures of this composition lead-free summer gasolines A92, A95, and A98 meeting US standards and purchased in the USA under the trademarks Phillips J Base Fuel, Union Clear Base and Indolene, were used. The source gasolines comprised aliphatic and alicyclic C5-C12 hydrocarbons, including both saturated and unsaturated ones. Fig. 1 shows the behaviour of the DVPE of the ethanol-containing motor fuel based on US summer grade A92 gasoline. The ethanol-containing motor fuels based on US summer A95 and A98 gasolines, respectively, demonstrated similar behaviour. The US summer A92 gasoline had the following specification: DVPE = 47,8 kPa Anti-knock index 0.5(RON + MON)=87.7 The fuel 3- 1 contained US A92 summer gasoline and ethanol and had the following properties for the various compositions: A92 : Ethanol = 95 : 5 % by volume DVPE = 55.9 kPa 0.5(RON + MON) = 89.0 A92 : Ethanol = 90 : 10 % by volume DVPE = 55.4 kPa 0.5(RON + MON) = 90.1 The fuel 3-2 contained US A92 summer gasoline, ethanol, and the oxygen- containing additives and had the following properties for the various compositions: A92 : Ethanol : Isoamyl alcohol = 83 : 8.5 : 8.5 % by volume DVPE = 47.5 kPa 0.5(RON + MON) = 89.6 A92 : Ethanol : Isoamyl propionate = 82 : 8 : 10 % by volume DVPE = 47.0 kPa 0.5(RON + MON) = 89.9 A92 : Ethanol : 2-Ethylhexanol = 82 : 8 : 10 % by volume DVPE = 47.8 kPa 0.5(RON + MON) = 89.2 A92 : Ethanol : Tetrahydrofurfuryl alcohol = 82 : 7 : 10 % by volume DVPE = 47.8 kPa 0.5(RON + MON) = 89.3 A92 : Ethanol : Cyclohexanone = 82 : 7 : 10 % by volume DVPE = 47.7 kPa 0.5(RON + MON) = 89.1 A92 : Ethanol : Methoxybenzene = 80 : 8.5 : 11.5 % by volume DVPE = 46.8 kPa 0.5(RON + MON) = 90.6 A92 : Ethanol : Methoxytoluene = 82 : 8 : 10 % by volume DVPE = 46.5 kPa 0.5(RON + MON) = 90.8 A92 : Ethanol : Methylbenzoate = 82 : 8 : 10 % by volume DVPE = 46.0 kPa 0.5(RON + MON) = 90.5 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by the presence of ethanol to the level of the DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the US summer grade gasoline is 7 psi, which corresponds to 48.28 kPa. A92 : Ethanol : Isoamyl alcohol = 83 : 9 : 8 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 89.8 A92 : Ethanol : Methoxytoluene = 84 : 8 : 8 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 90.5 A92 : Ethanol : Methylbenzoate = 85 : 8 : 7 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 90.1 The fuel 3-3 contained US A92 summer gasoline (a), ethanol (b), the oxygen- containing additives (c), and C 6 -Ci2 hydrocarbons (d) and had the following proper- ties for the various compositions: A92 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha = 75 : 9.2 : 0.3 : 0.1 : 15.4 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 47.8 kPa 0.5(RON + MON) = 89.5 A92 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : m-Isopropyltoluene = 75 : 9.2 : 0.3 : 0.1 : 15.4 % by volume DVPE = 47.0 kPa 0.5(RON + MON) = 90.5 A92 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Isooctane = 75 : 9.2 : 0.3 : 0.1 : 15.4 % by volume DVPE = 47.8 kPa 0.5(RON + MON) = 90.3 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by the presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the US summer grade gasoline is 7 psi, which corresponds to 48.28 kPa. A92 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha = 76 : 9.2 : 0.3 : 0.1 : 14.4 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 48.2 kPa 0.5(RON + MON) = 89.6 A92 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha : Isooctane = 76 : 9.2 : 0.3 : 0.1 : 10.4 : 4 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 48.2 kPa 0.5(RON + MON) = 89.8 A92 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha : m-Isopropyl toluene = 77 : 9.2 : 0.3 : 0.1 : 10.4 : 3 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 48.2 kPa 0.5(RON + MON) = 89.9 The following fuels demonstrate the possibility of adjusting the dry vapour pressure equivalent (DVPE) of the ethanol-containing motor fuel based on US A98 summer gasoline. The US A98 gasoline had the following specification: DVPE = 48.2 kPa Anti-knock index 0.5(RON + MON)= 92.2 The comparative fuel 3-4 contained US A98 summer gasoline and ethanol and had the following properties for the various compositions: A98 : Ethanol = 95 : 5 % by volume DVPE = 56.3 kPa 0.5(RON + MON) = 93.0 A98 : Ethanol = 90 : 10 % by volume DVPE = 55.8 kPa 0.5(RON + MON) = 93.6 The fuel 3-5 contained US A98 summer gasoline (a), ethanol (b) and the oxygen- containing additives (c), and had the following properties for the various compositions: A98 : Ethanol : Isoamyl alcohol = 82.5 : 9 : 8.5 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 93.3 A98 : Ethanol : Isoamyl alcohol : Isobutyl alcohol = 82.5 : 9 : 7 : 1.5 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 93.4 A98 : Ethanol : Tetrahydrofurfuryl alcohol = 80 : 10 : 10 % by volume DVPE = 48.0 kPa 0.5(RON + MON) = 93.7 The fuel 3-6 contained US A98 summer gasoline (a), ethanol (b), the oxygen- containing additives (c), and Cβ-Ci2 hydrocarbons (d) and had the following properties for the various compositions: A98 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha = 75 : 9.2 : 0.3 : 0.1 : 15.4 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 48.2 kPa 0.5(RON + MON) = 93.3 A98 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Isooctane = 75 : 9.2 : 0.3 : 0.1 : 15.4 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 93.9 A98 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : m-Isopropyltoluene = 75.5 : 9.2 : 0.3 : 0.1 : 14.9 % by volume DVPE = 47.5 kPa 0.5(RON + MON) = 94.4 A98 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha : Isooctane = 75 : 9.2 : 0.3 : 0.1 : 8.4 : 7 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 48.2 kPa 0.5(RON + MON) = 93.6 A98 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha : m-Isopropyl toluene = 75 : 9.2 : 0.3 : 0.1 : 10.4 : 5 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 48.0 kPa 0.5(RON + MON) = 93.7 A98 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha : Alkylate = 75 : 9.2 : 0.3 : 0.1 : 7.9 : 7.5 % by volume The boiling temperature for the naphtha is 100-200°C. The boiling temperature for the alkylate is 100-130°C. DVPE = 48.2 kPa 0.5(RON + MON) = 93.6 The following fuels demonstrated the possibility of adjusting the dry vapour pressure equivalent (DVPE) of the ethanol-containing motor fuel based on US summer A95 gasoline. The US summer A95 gasoline had the following specification: DVPE = 47.0 kPa Anti-knock index 0.5(RON + MON) = 90.9 The US summer A95 gasoline was used as a reference fuel for the testing performed according to EU2000 NEDC EC 98/69 test cycle on a 1987 Volvo 240 DL with a B230F, 4-cylinder, 2.32 litre engine (No. LG4F20-87) developing 83 kW at 90 revolutions/second and a torque of 185 Nm at 46 revolutions/second. The testing performed as above demonstrated for the US summer A95 gasoline the following results: CO (carbon monoxide) 2.406g/km HC (hydrocarbons) 0.356g/km NOx (nitrogen oxides) 0.278g/km CO2 (carbon dioxide) 232.6g/km NMHC* 0.258g/km Fuel consumption, F c 1/ 100km 9.93 * Non-methane hydrocarbons. The comparative fuel 3-7 contained US A95 summer gasoline and ethanol and had the following properties for the various compositions: A95 : Ethanol = 95 : 5 % by volume DVPE = 55.3 kPa 0.5(RON + MON) = 91.5 A95 : Ethanol = 90 : 10 % by volume DVPE = 54.8 kPa 0.5(RON + MON) = 92.0 Testing of the reference gasoline- alcohol mixture (RFM3) comprising 90 % by volume of US A95 summer grade gasoline and 10 % by volume of ethanol performed on a 1987 Volvo 240 DL with a B230F, 4-cylinder, 2.32 litre engine (No. LG4F20-87) in accordance with the standard test method EU 2000 NEDC EC 98/69 demonstrated the following results, as compared to summer US A95 gasoline: CO -12.5%; HC -4.8%; NOx +2.3%; C0 2 +3.7%; NMHC* -4.0%; Fuel consumption, F, 1/ 100km +3.1% "-" represents a reduction in emission, while "+" represents an increase in emission. The fuel 3-8 contained US A95 summer gasoline, ethanol and the oxygen- containing additives, and had the following properties for the various compositions: A95 : Ethanol : Isoamyl alcohol = 83 : 8.5 : 8.5 % by volume DVPE = 47.0 kPa 0.5(RON + MON) = 91.7 A95 : Ethanol : n-Amyl acetate = 80 : 10 : 10 % by volume DVPE = 47.0 kPa 0.5(RON + MON) = 91.8 A95 : Ethanol : Cyclohexylacetate = 80 : 10 : 10 % by volume DVPE = 46.7 kPa 0.5(RON + MON) = 92.0 A95 : Ethanol : Tetramethyltetrahydrofurane = 80 : 12 : 8 % by volume DVPE = 47.0 kPa 0.5(RON + MON) = 92.6 A95 : Ethanol : Methyltetrahydropyrane = 80 : 15 : 5 % by volume DVPE = 46.8 kPa 0.5(RON + MON) = 92.5 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by the presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the US summer grade gasoline is 7 psi, which corresponds to 48.28 kPa. A95 : Ethanol : Isoamyl alcohol = 84 : 8.5 : 7.5 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 91.7 A95 : Ethanol : Phenylacetate = 82.5 : 10 : 7.5 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 92.3 A95 : Ethanol : Tetramethyltetrahydrofurane = 81 : 10 : 9 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 92.2 The fuel 3-9 contained US A95 summer gasoline (a), ethanol (b), the oxygen- containing additives (c), and C6-C12 hydrocarbons (d) and had the following properties for the various compositions: A95 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha = 75 : 9.2 : 0.3 : 0.1 : 15.4 % by volume The boiling temperature for the naphtha is 100-200°C DVPE = 47.0 kPa 0.5(RON + MON) = 91.6 A95 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Isooctane = 75 : 9.2 : 0.3 : 0.1 : 15.4 % by volume DVPE = 47.0 kPa 0.5(RON + MON) = 92.2 A95 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : m-Isopropyltoluene = 75 : 9.2 : 0.3 : 0.1 : 15.4 % by volume DVPE = 46.8 kPa 0.5(RON + MON) = 93.0 A95 : Ethanol : Tetrahydrofurfuryl alcohol : Cyclooctatetraene = 80 : 9.5 : 0.5 : 10 % by volume DVPE = 46.6 kPa 0.5(RON + MON) = 92.5 A95 : Ethanol : 4-Methyl-4-oxytetrahydropyrane : Allocymene = 80 : 9.5' : 0.5 : 10 % by volume DVPE = 46.7 kPa 0.5(RON + MON) = 92.1 The motor fuel compositions below demonstrate that it is not always necessary to reduce the excess DVPE of the motor fuel caused by the presence of ethanol to the level of DVPE of the source gasoline. In some cases it is sufficient just to bring it in compliance with the requirements of the regulations in force for the corresponding gasoline. The DVPE level for the US summer grade gasoline is 7 pSi, which corresponds to 48.28 kPa. A95 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha = 76.5 : 9.2 : 0.3 : 0.1 : 7 : 6,9 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 48.2 kPa 0.5(RON + MON) = 91.7 A95 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : Naphtha : Isooctane = 76.5 : 9.2 : 0.3 : 0.1 : 7 : 6.9 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 48.2 kPa 0.5(RON + MON) = 92.2 A95 : Ethanol : Isoamyl alcohol : Isobutyl alcohol : m-Isopropyltoluene = 77 : 9.2 : 0.3 : 0.1 : 13.4 % by volume DVPE = 48.2 kPa 0.5(RON + MON) = 92.9 The fuel formulation 3-10 contained 76 % by volume of US A95 summer gasoline, 9.2 % by volume of ethanol, 0.25 % by volume of isoamyl alcohol, 0.05 % by volume of isobutyl alcohol, 11.5 % by volume of naphtha with boiling temperature of 100- 200°C, and 3 % by volume of isopropyltoluene. Formulation 3- 10 was tested to demonstrate how the invention enables the production of ethanol-containing gasoline entirely meeting the requirements of the standards in force, firstly for the level of the DVPE and also for the other parameters. At the same time this gasoline se- cures a decrease of toxic emissions in the exhaust and lower fuel consumption in comparison to the mixture RFM 3 of source US A95 summer gasoline with 10% of ethanol. Formulation 3-10 had the following specific properties: density at 15°C, according to ASTM D4052 774.9kg /m3; initial boiling point, according to ASTM D 86 36.1°C; vaporisable portion - 70°C 33.6 % by volume; vaporisable portion - 100°C 50.8 % by volume; vaporisable portion - 150°C 86.1 % by volume; vaporisable portion - 190°C 97.0 % by volume; final boiling point 204.8°C; evaporation residue 1.5 % by volume; loss by evaporation 1.5 % by volume; oxygen content, according to ASTM D4815 3.37% w/w; acidity, according to ASTM D1613 weight% HAc 0.007; pH, according to ASTM D1287 7.58; sulfur content, according to ASTM D 5453 47mg/kg; gum content, according to ASTM D381 2.8mg/ 100ml; water content, according to ASTM D6304 0.02% w/w; aromatics, according to SS 155120, including benzene 31.2 % by volume; benzene alone, according to EN 238 0.7 % by volume; DVPE, according to ASTM D 5191 48.0kPa; anti-knock index 0.5(RON+MON), according to ASTM D 2699-86 and ASTM D 2700-86 92.2 The motor fuel Formulation 3-10 was tested on a 1987 Volvo 240 DL with a B230F, 4- cylinder, 2.32 litre engine (No. LG4F20-87) in accordance with test method EU 2000 NEDC EC 98/69 as above and gave the following results in comparison (+) or (-)% with the results for the source US A95 summer gasoline: CO -15.1% HC -5.6%; NOx +0.5%; C02 unchanged; NMHC -4.5%; Fuel consumption, Fc, 1/ 100km unchanged. Similar results were obtained when the other oxygen- containing compounds substituted the tested oxygen- containing compounds. To prepare all the fuel formulations above, initially US summer gasoline was mixed with ethanol, to which mixture was then added the corresponding oxygen- containing additive. The motor fuel composition obtained was then allowed to stand before testing between 1 and 24 hours at a temperature not lower than -35°C. All the above formulations were prepared without the use of any mixing devices. It was established the possibility of employing of the additive mixture comprising ethanol and oxygen- containing compounds other than ethanol also for adjustment of the vapour pressure of the ethanol-containing motor fuels used in standard in- ternal combustion spark ignition engines based on summer grade gasolines meeting US standards. Adding Cs-Ci2 hydrocarbons to the composition of the additive mixture increased the efficiency of the vapour pressure reducing impact of the additive on the excess vapour pressure caused by presence in the gasoline of ethanol. The additive mixture comprising 60 % by volume of ethanol, 32 % by volume of isoamyl alcohol and 8 % by volume of isobutyl alcohol was in different proportions mixed with US summer grade gasolines having dry vapour pressure equivalent (DVPE) not higher than 7 psi, which corresponds 48.28 kPa. The compositions obtained had the following properties: A92 : Ethanol : Isoamyl alcohol : Isobutanol = 87.5 : 7.5 : 4 : 1 % by volume DVPE = 51.7 kPa 0.5(RON + MON) = 89.7 A95 : Ethanol : Isoamyl alcohol : Isobutanol = 85 : 9 : 4.8 : 1.2 % by volume DVPE = 51.0 kPa 0.5(RON + MON) = 91.8 A98 : Ethanol : Isoamyl alcohol : Isobutanol = 80 : 12 : 6.4 : 1.6 % by volume DVPE = 52.0 kPa 0.5(RON + MON) = 93.5 The foregoing examples demonstrate the possibility of partially lowering the excess vapour pressure, by about 50% of the excess vapour pressure of gasoline induced by the presence of ethanol in the mixture. An additive mixture comprising 50 % by volume of ethanol and 50 % by volume of methylisobutyl ketone was mixed in different proportions with US summer grade gasoline with dry vapour pressure equivalent (DVPE) not higher than 7 psi, which corresponds to 48.28 kPa. The compositions obtained had the following properties: A92 : Ethanol : Methylisobutyl ketone = 85 : 7.5 : 7.5 % by volume DVPE = 49.4 kPa 0.5(RON + MON) = 90.0 A95 : Ethanol : Methylisobutyl ketone = 84 : 8 : 8 % by volume DVPE = 48.6 kPa 0.5(RON + MON) = 91.7 A98 : Ethanol : Methylisobutyl ketone = 82 : 9 : 9 % by volume DVPE = 49.7 kPa 0.5(RON + MON) = 93.9 The foregoing examples demonstrate the possibility of a partial lowering of the excess vapour pressure by about 80% of the excess vapour pressure of gasoline induced by the presence of ethanol in the mixture. Figure 2 shows the behaviour of the dry vapour pressure equivalent (DVPE) as a function of the ethanol content in the mixtures of US summer A92 gasoline and the additive mixture 4 comprising 35 % by volume of ethanol, 1 % by volume of isoamyl alcohol, 0.2 % by volume of isobutanol, 43.8 % by volume of naphtha boiling at temperatures between 100-170°C, and 20% of isopropyl toluene. Figure 2 demonstrates that employment of this additive mixture in formulation of ethanol-containing gasoline enables the reduction of more than 100% of the excess vapour pressure induced by the presence of ethanol. Similar results for DVPE were obtained for US summer grade A95 and A98 gasoline mixed with the additive mixture composed of 35 % by volume of ethanol, 1 % by volume of isoamyl alcohol, 0.2 % by volume of isobutanol, 43.8 % by volume of naphtha boiling at 100-170°C and 20% by volyme of isopropyltoluene. Similar results were obtained when other oxygen- containing compounds and C6-C12 hydrocarbons of this invention were used in the proportion established by this invention to formulate the additive mixture, which was then used for preparation of the ethanol-containing gasolines. These gasolines entirely meet the requirements for the motor fuels used in standard internal combustion spark ignition engines. Moreover, the additive mixture comprising ethanol, the oxygen-containing compound other than ethanol, and C 6 -Ci2 hydrocarbons in the proportion and composition of the present invention, can be used as an independent motor fuel for the engines adopted for operation on ethanol. EXAMPLE 4 Example 4 demonstrates the possibility of reducing the dry vapour pressure equivalent of the ethanol-containing motor fuel for the cases when the hydrocarbon base of the fuel is a non-standard gasoline with a dry vapour pressure equivalent according to ASTM D-5191 at a level of 110 kPa (about 16 psi). To prepare the mixtures of this composition lead-free winter gasoline A92, A95, and A98 purchased in Sweden from Shell, Statoil, Q80K and Preem and gas condensate (GK) purchased in Russia from Gazprom were used. The hydrocarbon component (HCC) for the motor fuel compositions was prepared by mixing about 85 % by volume of winter A92, A95 or A98 gasoline with about 15 % by volume of gas condensate hydrocarbon liquid (GC) . To prepare the hydrocarbon component (HCC) for the fuel formulations 4-1 to 4-10 of this motor fuel composition, about 85 % by volume of winter A92, A95 or A98 gasoline was first mixed with the gas condensate hydrocarbon liquid (GC). The obtained hydrocarbon component (HCC) was then allowed to stand for 24 hours. The resulting gasoline contained aliphatic and alicyclic C3-C12 hydrocarbons, including saturated and unsaturated ones. Fig. 1 demonstrates the behaviour of the DVPE of the ethanol-containing motor fuel based on winter A98 gasoline and gas condensate. The ethanol-containing motor fuel based on winter A92 and A98 gasoline and gas condensate (GC) demonstrated similar behaviour. Gasoline comprising 85 % by volume of winter gasoline A92 and 15 % by volume of gas condensate (GC) had the following properties: DVPE = HO.O kPa Anti-knock index 0.5(RON + MON)=87.9 The comparative fuel 4-1 contained A92 winter gasoline, gas condensate (GC) and ethanol and had the following properties for the various compositions: A92 : GC : Ethanol= 80.75 : 14.25 : 5 % by volume DVPE = 115.5 kPa 0.5(RON + MON) = 89.4 A92 : GC : Ethanol= 76.5 : 13.5 : 10 % by volume DVPE = 115.0 kPa 0.5(RON + MON) = 90.6 The inventive fuel 4-2 contained A92 winter gasoline, gas condensate (GC), ethanol and the oxygen-containing additive and had the following properties for the various compositions: A92 : GC : Ethanol : Isoamyl alcohol = 74 : 13 : 6.5 : 6.5 % by volume DVPE = 109.8 kPa 0.5(RON + MON) = 90.35 A92 : GC : Ethanol : 2,5 Dimethyltetrahydrofuran = 68 : 12 : 10 : 10 % by volume DVPE = HO.O kPa 0.5(RON + MON) = 90.75 A92 : GC : Ethanol : Propanol = 68 : 12 : 12 : 8 % by volume DVPE = 109.5 kPa 0.5(RON + MON) = 90.0 A92 : GC : Ethanol : Diisopropylcarbinol = 72 : 13 : 7.5 : 7.5 % by volume DVPE = 109.0 kPa 0.5(RON + MON) = 90.3 A92 : GC : Ethanol : Acetophenone = 72 : 13 : 9 : 6 % by volume DVPE = HO.O kPa 0.5(RON + MON) = 90.8 A92 : GC : Ethanol : Isobutylpropionate = 75 : 13 : 5 : 7 % by volume DVPE = 109.2 kPa 0.5(RON + MON) = 90.0 The fuel 4-3 contained winter A92 gasoline, gas condensate (GC), ethanol, the oxy- gen- containing additive and C6-C12 hydrocarbons and had the following properties for the various compositions: A92 : GC : Ethanol : Isobutanol : Isopropylbenzene = 68 : 12 : 9.5 : 0.5 : 10 % by volume DVPE = 108.5 kPa 0.5(RON + MON) = 91.7 A92 : GC : Ethanol : Tert-butylethyl ether : Naphtha = 68 : 12 : 9.5 : 0.5 : 10 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 108.5 kPa 0.5(RON + MON) = 90.6 A92 : GC : Ethanol : Isoamylmethyl ether : Toluene = 68 : 12 : 9.5 : 0.5 : 10 % by volume DVPE = 107.5 kPa 0.5(RON + MON) = 91.6 The fuel compositions below demonstrate that the invention enables the reduction of the excess DVPE of the non-standard gasoline to the level of the corresponding standrd gasoline. The DVPE for the standard A92 winter gasoline is 90 kPa. A92 : GC : Ethanol : Isoamyl alcohol : Naphtha : Alkylate = 55 : 10 : 9.5 : 0.5 : 12.5 : 12.5 % by volume The boiling temperature for the naphtha is 100-200°C. The boiling temperature for the alkylate is 100-130°C. DVPE = 90.0 kPa 0.5(RON + MON) = 90.6 A92 : GC : Ethanol : Isoamyl alcohol : Naphtha : Ethylbenzene = 55 : 10 : 9.5 : 0.5 : 15 : 10 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 89.8 kPa 0.5(RON + MON) = 90.9 A92 : GC : Ethanol : Isoamyl alcohol : Naphtha : Isopropyltoluene = 55 : 10 : 9.5 : 0.5 : 20 : 5 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 90.0 kPa 0.5(RON + MON) = 90.6 The following compositions demonstrate the possibility of adjusting the dry vapour pressure equivalent (DVPE) of the ethanol-containing fuel mixtures based on about 85 % by volume of winter A98 gasoline and about 15 % by volume of gas condensate. The gasoline comprising 85 % by volume of winter A98 gasoline and 15 % by volume of gas condensate (GC) had the following specification: DVPE = 109.8 kPa Anti-knock index 0.5(RON + MON)=92.0 The comparative fuel 4-4 contained A98 winter gasoline, gas condensate (GC) and ethanol and had the following properties for the various compositions: A98 : GC : Ethanol = 80.75 : 14.25 : 5 % by volume DVPE = 115.3 kPa 0.5(RON + MON) = 93.1 A98 : GC : Ethanol = 76.5 : 13.5 : 10 % by volume DVPE = 114.8 kPa 0.5(RON + MON) = 94.0 The inventive fuel 4-5 contained A98 winter gasoline, gas condensate (GC) and the oxygen-containing additives and had the following properties for the various compositions: A98 : GC : Ethanol : Isoamyl alcohol = 74 : 13 : 6.5 : 6.5 % by volume DVPE = 109.6 kPa 0.5(RON + MON) = 93.3 A98 : GC : Ethanol : Ethoxybenzene = 72 : 13 : 7.5 : 7.5 % by volume DVPE = HO.O kPa 0.5(RON + MON) = 94.0 A98 : GC : Ethanol : 3,3,5 Trimethylcyclohexanone = 72 : 13 : 7.5 : 7.5 % by volume DVPE = 109.8 kPa 0.5(RON + MON) = 93.3 The fuel 4-6 contained A98 winter gasoline, gas condensate, ethanol, the oxygen- containing additives, and Cβ-Ci2 hydrocarbons (d) and had the following properties for the various compositions: A98 : GC : Ethanol: Isoamyl alcohol : Isobutyl alcohol : Naphtha = 68 : 12 : 9.2 : 0.6 : 0.2 : 10 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 107.4 kPa 0.5(RON + MON) = 93.8 A98 : GC : Ethanol : Ethylisobutyl ether : Myrzene = 72 : 13 : 9.5 : 0.5 : 5 % by volume DVPE = 110.0 kPa 0.5(RON + MON) = 93.6 A98 : GC : Ethanol : Isobutanol : Isooctane = 68 : 12 : 5 : 5 : 10 % by volume DVPE = 102.5 kPa 0.5(RON + MON) = 93.5 The motor fuel compositions below demonstrate that the invention enables the reduction of the excess DVPE of non-standard gasoline to the level of DVPE of the corresponding standard gasoline. The DVPE for the standard winter A98 gasoline is 90.0 kPa. A92 : GC : Ethanol : Isoamyl alcohol : Naphtha : Alkylate = 55 : 10 : 9.5 : 0.5 : 12.5 : 12.5 % by volume The boiling temperature for the naphtha is 100-200°C. The boiling temperature for the alkylate is 100-130°C. DVPE = 89.8 kPa 0.5(RON + MON) = 94.0 A92 : GC : Ethanol : Isoamyl alcohol : Naphtha : Isopropylbenzene = 55 : 10 : 9.5 : 0.5 : 15 : 10 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 89.6 kPa 0.5(RON + MON) = 94.2 A92 : GC : Ethanol : Isobutanol : Naphtha : Isopropyltoluene = 55 : 10 : 5 : 5 : 20 : 5 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 88.5 kPa 0.5(RON + MON) = 94.1 The following compositions demonstrate the possibility of adjusting the dry vapour pressure equivalent (DVPE) of the ethanol-containing fuel mixtures based on about 85 % by volume of winter A95 gasoline and about 15 % by volume of gas condensate. The gasoline comprising 85 % by volume of winter A98 gasoline and 15 % by volume of gas condensate (GC) had the following specification: DVPE = 109.5 kPa Anti-knock index 0.5(RON + MON)=90.2 The hydrocarbon component (HCC) comprising 85 % by volume of winter gasoline and 15 % by volume of gas condensate (GC) was used as a reference fuel for testing as described above and gave the following results: CO 2.033 g/km HC * 0.279 g/km NOx 0.279 g/km C0 2 229.5 g/km NMHC 0.255 g/km Fuel consumption, Fc, 1/ 100km 9.89 The fuel 4-7 contained A95 winter gasoline, gas condensate (GC) and ethanol and had the following properties for the various compositions: A95 : GC : Ethanol = 80.75 : 14.25 : 5 % by volume DVPE = 115.0 kPa 0.5(RON + MON) = 91.7 A95 : GC : Ethanol = 76.5 : 13.5 : 10 % by volume DVPE = 114.5 kPa 0.5(RON + MON) = 92.5 The reference fuel mixture (RFM4) comprising 80.75% of winter A95 gasoline, 14.25% of gas condensate (GC) and 5% of ethanol was tested as described above and gave the following results in comparison (+) or (-)% with the results for the gasoline comprising 85 % by volume of winter gasoline A95 and 15 % by volume of gas condensate (GC): CO -6.98% HC -7.3%; NOx +12.1%; C02 +1.1%; NMHC -5.3%; Fuel consumption, Fc, 1/ 100km +2.62%. The inventive fuel 4-8 contained A95 winter gasoline, gas condensate (GC), ethanol and the oxygen-containing additives and had the following properties for the various compositions: A95 : GC : Ethanol : Isoamyl alcohol = 74 : 13 : 6.5 : 6.5 % by volume DVPE = 109.1 kPa 0.5(RON + MON) = 92.0 A95 : GC : Ethanol : Phenol = 72 : 13 : 8 : 7 % by volume DVPE = 107.5 kPa 0.5(RON + MON) = 92.6 A95 : GC : Ethanol : Phenyl acetate = 68 : 12 : 10 : 10 % by volume DVPE = 106.0 kPa 0.5(RON + MON) = 92.8 A95 : GC : Ethanol : 3-Hydroxy-2-butanone = 68 : 12 : 10 : 10 % by volume DVPE = 108.5 kPa 0.5(RON + MON) = 91.6 A95 : GC : Ethanol : Tert-butylacetoacetate = 68 : 12 : 10 : 10 % by volume DVPE = 108.0 kPa 0.5(RON + MON) = 92.2 A95 : GC : Ethanol : 3,3.5-Trimethylcyclohexanone = 71 : 12 : 9 : 8 % by volume DVPE = 108.5 kPa 0.5(RON + MON) = 91.6 The fuel 4-9 contained A95 winter gasoline, gas condensate (GC), ethanol, the oxygen-containing additives, and C6-C12 hydrocarbons (d) and had the following properties for the various compositions: A95 : GC : Ethanol: Isoamyl alcohol : Isobutyl alcohol : Naphtha = 68 : 12 : 9.2 : 0.6 : 0.2 : 10 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 107.0 kPa 0.5(RON + MON) = 92.1 A95 : GC : Ethanol: Isobutanol : Cyclooctatetraene = 72 : 13 : 9.5 : 0.5 : 5 % by volume DVPE = 108.5 kPa 0.5(RON + MON) = 92.6 The motor fuel compositions below demonstrate that the invention enables the reduction of the excess vapour pressure equivalent (DVPE) of the non-standard gasoline to the level of the corresponding standard gasoline. The DVPE of the standard winter gasoline A95 is 90.0 kPa. A95 : GC : Ethanol: Isoamyl alcohol : Isobutanol : Naphtha : Alkylate = 55 10 : 9.2 : 0.6 : 0.2 : 12.5 : 12.5 % by volume The boiling temperature for the naphtha is 100-200°C. The boiling temperature for the alkylate is 100-130°C. DVPE = 89.5 kPa 0.5(RON + MON) = 92.4 A95 : GC : Ethanol: Isoamyl alcohol : Naphtha : Tert-butylxylene = 55 : 10 9.5 : 0.5 : 20 : 5 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 89.8 kPa 0.5(RON + MON) = 92.5 A95 : GC : Ethanol: Isobutanol : Naphtha : Isopropylbenzene = 55 : 10 : 5 : 5 : 20 : 5 % by volume The boiling temperature for the naphtha is 100-200°C. DVPE = 89.9 kPa 0.5(RON + MON) = 92.2 The motor fuel 4-10 contained 55% by volume of A95 winter gasoline, 10% by volume of gas condensate (GC), 5% by volume of ethanol, 5% by volume of tert- butanol, 20% by volume of naphtha with boiling temperature of 100-200°C and 5% by volume of isopropyltoluene. Formulation 4-10 was tested to demonstrate how the invention enables the formulation of ethanol-containing gasoline entirely meeting requirements of the standards in force, firstly in respect of the dry vapour pressure equivalent limit, and also for the other parameters of the fuel, even when the source hydrocarbon component (HCC) has a DVPE considerably higher than the require- ments of the standards. At the same time this ethanol-containing gasoline decreases the level of toxic emissions in the exhaust and decreases the fuel consumption in comparison with the above-described mixture RFM 4. The formulation 4-10 had the following specific properties: density at 15°C, according to ASTM D4052 698.6 kg /m3; initial boiling point, according to ASTM D 86 20.5°C; vaporisable portion - 70°C 47.0 % by volume; vaporisable portion - 100°C 65.2 % by volume; vaporisable portion - 150°C 92.4 % by volume; vaporisable portion - 180°C 97.3 % by volume; final boiling point 189.9°C; evaporation residue 0.5 % by volume; loss by evaporation 1.1 % by volume; oxygen content, according to ASTM D4815 3.2% w/w; acidity, according to ASTM D1613 weight% HAc 0.001; pH, according to ASTM D1287 7.0; sulfur content, according to ASTM D 5453 18 mg/kg; gum content, according to ASTM D381 2 mg/ 100ml; water content, according to ASTM D6304 0.01% w/w; aromatics, according to SS 155120, including benzene 30.9 % by volume; benzene alone, according to EN 238 0.7 % by volume; DVPE, according to ASTM D 5191 90.0 kPa; anti-knock index 0.5(RON+MON), according to ASTM D 2699-86 and ASTM D 2700-86 92.3 The motor fuel Formulation 4-10 was tested as above and gave the following results in comparison (+) or (-)% with the results for the motor fuel comprising 85 % by volume of winter A95 gasoline and 15 % by volume of gas condensate: CO - 14.0% HC -8.6%; NOx unchanged; C0 2 +1.0%; NMHC -6.7%; Fuel consumption, Fc, 1/ 100km +2.0% Similar results are obtained when other oxygen- containing additives of the invention are substituted for the oxygen-containing additives of the examples 4- 1 to 4-10. To prepare all the above fuel formulations 4-1 to 4-10 of this motor fuel composition, the hydrocarbon component (HCC), which is a mixture of winter gasoline and gas condensate (GC), was initially mixed with ethanol, to which mixture then was added the corresponding oxygen-containing additive and C6-C12 hydrocarbons. The motor fuel composition obtained was then allowed to stand before testing between 1 and 24 hours at a temperature not lower than -35°C. All the above formulations were prepared without the use of any mixing devices. The inventive fuel formulations demonstrated the possibility of adjusting the vapour pressure of the ethanol-ccontaining motor fuels for the standard internal combus- tion spark ignition engines based on non-standard gasolines having a high vapour pressure. Figure 2 shows the behaviour of the dry vapour pressure equivalent (DVPE) as a function of the ethanol content of the mixtures of the hydrocarbon component (HCC), comprising 85 % by volume of winter A98 gasoline and 15 % by volume of gas condensate, and the additive mixture 1, comprising 40 % by volume of ethanol and 60 % by volume of methylbenzoate. Figure 2 demonstrates that employment of this additive mixture comprising ethanol and the oxygen-containing additive other than ethanol enables to obtain ethanol- containing gasolines, the vapour pressure of which does not exceed the vapour pressure of the source hydrocarbon component (HCC) . Similar results for DVPE were obtained for the fuel mixtures of the additive mixture, comprising 40 % by volume of ethanol and 60 % by volume of methylbenzoate, and hydrocarbon component comprising 15 % by volume of gas condensate (GC) and 85 % by volume of A92 or A95 winter gasoline. Similar results were obtained when other oxygen-containing compounds and C6-C12 hydrocarbons of this invention were used in the proportion of the invention to formulate the additive mixture, which was then used for preparation of the ethanol- containing gasolines. These gasoline mixtures of the invention have a vapour pressure equivalent (DVPE) which does not exceed the DVPE of the source hydrocarbon component (HCC). At the same time it is possible to add the oxygen-containing additive only in the amount sufficient to obtain the ethanol-containing gasoline entirely in compliance with requirements for the motor fuels used in the standard internal combustion spark ignition engines. EXAMPLE 5 Example 5 demonstrates the possibility of reducing the dry vapour pressure equivalent of the ethanol-containing motor fuel for the cases when the hydrocarbon base of the fuel is a reformulated gasoline with dry vapour pressure equivalent according to ASTM D-5191 at a level of 27.5 kPa (about 4 psi). To prepare the mixtures of this composition lead-free reformulated gasoline pur- chased in Sweden from Preem and in Russia from Lukoil, and the Petroleum benzine purchased from Merck in Germany were used. The hydrocarbon component (HCC) for the motor fuel compositions was prepared by mixing about 85 % by volume of winter A92, A95 or A98 gasoline with about 15 % by volume of gas condensate hydrocarbon liquid (GC). The source gasolines comprised aliphatic and alicyclic C6-C12 hydrocarbons, including saturated and unsaturated. Fig. 1 demonstrates the behaviour of the DVPE of the ethanol-containing motor fuel based on reformulated gasoline A92 and Petroleum benzine. Similar behaviour was observed for the ethanol-containing motor fuel based on reformulated A95 and A98 gasoline, and Petroleum benzine. It should be pointed out that addition of ethanol to the reformulated gasoline induces a higher vapour pressure increase compared to the addition of ethanol to the standard gasoline. Gasoline comprising 80 % by volume of reformulated gasoline A92 and 20 % by volume of Petroleum benzine (PB) had the following properties: DVPE = 27.5 kPa Anti-knock index 0.5(RON + MON)=85.5 The comparative fuel 5-1 contained A92 reformulated gasoline, Petroleum benzine (PB) and ethanol and had the following properties for the various compositions: A92 : PB : Ethanol= 76 : 19 : 5 % by volume DVPE = 36.5 kPa 0.5(RON + MON) = 89.0 A92 : PB : Ethanol= 72 : 18 : 10 % by volume DVPE = 36.0 kPa 0.5(RON + MON) = 90.7 The inventive fuel 5-2 contained A92 reformulated gasoline, Petroleum benzine (PB), ethanol and the oxygen- containing additive and had the following properties for the various compositions: A92 : PB : Ethanol : Isoamyl alcohol = 64 : 16 : 10 : 10 % by volume DVPE = 27.0 kPa 0.5(RON + MON) = 90.5 A92 : PB : Ethanol : Diisobutyl ether - 64 : 16 : 10 : 10 % by volume DVPE = 27.5 kPa 0.5(RON + MON) = 90.8 A92 : PB : Ethanol : n-Butanol = 64 : 16 : 10 : 10 % by volume DVPE = 27.5 kPa 0.5(RON + MON) = 90.1 A92 : PB : Ethanol : 2,4,4-Trimethyl-l-pentanol = 64 : 16 : 10 : 10 % by volume DVPE = 25.0 kPa 0.5(RON + MON) = 91.8 The fuel 5-3 contained reformulated A92 gasoline, Petroleum benzine (PB), ethanol, the oxygen- containing additives and also Cs-Ci2 hydrocarbons and had the following properties for the various compositions: A92 : PB : Ethanol : Isoamyl alcohol : Naphtha = 60 : 15 : 9.2 : 0.8 : 15 % by volume The boiling temperature for the naphtha is 140-200°C. DVPE = 27.5 kPa 0.5(RON + MON) = 89.3 A92 : PB : Ethanol : n-Butanol : Naphtha : Xylene = 60 : 15 : 9.2 : 0.8 : 7.5 : 7.5 % by volume The boiling temperature for the naphtha is 140-200°C. DVPE = 27.5 kPa 0.5(RON + MON) = 91.2 A92 : PB : Ethanol : Tetrahydrofurfuryl alcohol : Isopropylbenzene = 60 : 15 : 9 : 1 : 15 % by volume DVPE = 27.5 kPa 0.5(RON + MON) = 91.3 The fuel compositions below demonstrate the possibility of adjusting the dry vapour pressure equivalent of the ethanol-containing gasolines based on reformulated A98 gasoline and Petroleum benzine (PB) . The motor fuel comprising 80 % by volume of reformulated gasoline A98 and 20 % by volume of Petroleum benzine (PB) had the following properties: DVPE = 27.3 kPa Anti-knock index 0.5(RON + MON) = 88.0 The comparison fuel 5-4 contained A98 reformulated gasoline, Petroleum benzine (PB) and ethanol and had the following properties for the various compositions: A98 : PB : Ethanol = 76 : 19 : 5 % by volume DVPE = 36.3 kPa 0.5(RON + MON) = 91.0 A98 : PB : Ethanol = 72 : 18 : 10 % by volume DVPE = 35.8 kPa 0.5(RON + MON) = 92.5 The fuel 5-5 of the invention contained A98 reformulated gasoHne, Petroleum benzine (PB), ethanol and the oxygen-containing additives and had the following properties for the various compositions: A98 : PB : Ethanol : Isoamyl alcohol = 64 : 16 : 10 : 10 % by volume DVPE = 26.9 kPa 0.5(RON + MON) = 92.0 A98 : PB : Ethanol : n-Amyl alcohol = 64 : 16 : 10 : 10 % by volume DVPE = 26.5 kPa 0.5(RON + MON) = 91.2 A98 : PB : Ethanol : Linalool = 68 : 17 : 9 : 6 % by volume DVPE = 27.1 kPa 0.5(RON + MON) = 92.6 A98 : PB : Ethanol : 3,6-Dimethyl-3-octanol = 68 : 17 : 9 : 6 % by volume DVPE = 27.0 kPa 0.5(RON + MON) = 92.5 The fuel 5-6 contained A98 reformulated gasoline, Petroleum benzine (PB), ethanol, the oxygen-containing additives, and Cs-Ci2 hydrocarbons (d) and had the following properties for the various compositions: A98 : PB : Ethanol: Isoamyl alcohol : Naphtha = 60 : 15 : 9.2 : 0.8 : 15 % by volume The boiling temperature for the naphtha is 140-200°C. DVPE = 27.0 kPa 0.5(RON + MON) = 91.7 A98 : PB : Ethanol : Linalool : Allocymene = 60 : 15 : 9 : 1 : 15 % by volume DVPE = 26.0 kPa 0.5(RON + MON) = 93.0 A98 : PB : Ethanol : Methylcyclohexanol : Limonene = 60 : 15 : 9.5 : 1 : 14.5 % by volume DVPE = 25.4 kPa 0.5(RON + MON) = 93.2 The motor fuel compositions below demonstrate the possibility of adjusting the dry vapour pressure equivalent of the ethanol-containing fuel mixture based on about 80 % by volume of reformulated A95 gasoline and about 20 % by volume of the Petroleum benzine (PB). Gasoline comprising 80 % by volume of the reformulated A95 gasoline and 20 % by volume of the Petroleum benzine (PB) had the following properties: DVPE = 27.6 kPa Anti-knock index 0.5(RON + MON) = 86.3 The hydrocarbon component (HCC) comprising 80 % by volume of reformulated gasoline and 20 % by volume of Petroleum benzine (PB) was used as a reference fuel for testing on a 1987 Volvo 240 DL with a B230F, 4-cylinder, 2.32 litre engine (No. LG4F20-87) in accordance with test method EU 2000 NEDC EC 98/69 and gave the following results: CO 2.631 g/km HC 0.348 g/km; NOx 0.313 g/km C0 2 235.1 g/km NMHC 0.308 g/km Fuel consumption, Fc, 1/ 100km 10.68 The fuel 5-7 contained A95 reformulated gasoline, Petroleum benzine (PB) and ethanol and had the following properties for the various compositions: A95 : PB : Ethanol = 76 : 19 : 5 % by volume DVPE = 36.6 kPa 0.5(RON + MON) = 90.2 A95 : PB : Ethanol = 72 : 18 : 10 % by volume DVPE = 36.1 kPa 0.5(RON + MON) = 91.7 The reference fuel mixture (RFM5) comprising 72 % by volume of reformulated A95 gasoline, 18 % by volume of Petroleum benzine (PB) and 10 % by volume of ethanol was tested on a 1987 Volvo 240 DL with a B230F, 4-cylinder, 2.32 litre engine (No. LG4F20-87) in accordance with test method EU 2000 NEDC EC 98/69 as above and gave the following results in comparison (+) or (-)% with the results for the gasoline comprising 80 % by volume of reformulated gasoline A95 and 20 % by volume of Petroleum benzine (GC) : CO -4.8% HC -1.3%; NOx +26.3%; C02 +4.4%; NMHC -0.6%; Fuel consumption, Fc, 1/ 100km +5.7%. The fuel 5-8 contained A95 reformulated gasoline, Petroleum benzine (PB), ethanol and the oxygen-containing additives and had the following properties for the various compositions: A95 : PB : Ethanol : Isoamyl alcohol = 64 : 16 : 10 : 10 % by volume DVPE = 27.1 kPa 0.5(RON + MON) = 92.0 A95 : PB : Ethanol : 2,6-Dimethyl-4-heρtanol = 64 : 16 : 10 : 10 % by volume DVPE = 27.0 kPa 0.5(RON + MON) = 92.4 A95 : PB : Ethanol : Tetrahydrofurfuryl acetate = 60 : 15 : 15 : 10 % by volume DVPE = 25.6 kPa 0.5(RON + MON) = 93.0 The fuel 5-9 contained A95 reformulated gasoline, Petroleum benzine (PB), ethanol, the oxygen-containing additives, and Cs-Cι 2 hydrocarbons and had the following properties for the various compositions: A95 : PB : Ethanol: Isoamyl alcohol : Naphtha = 60 : 15 : 9.2 : 0.8 : 15 % by volume The boiling temperature for the naphtha is 140-200°C. DVPE = 27.1 kPa 0.5(RON + MON) = 91.4 A95 : PB : Ethanol: Tetrahydrofurfuryl alcohol : Tert-butylcyclohexane = 60 : 15 : 9.2 : 0.8 : 15 % by volume DVPE = 26.5 kPa 0.5(RON + MON) = 90.7 A95 : PB : Ethanol: 4-Methyl-4-hydroxytetrahydropyran : Isopropyltoluene = 60 : 15 : 9.2 : 0.8 : 15 % by volume DVPE = 26.1 kPa 0.5(RON + MON) = 92.0 The motor fuel 5-10 contained 60% by volume of A95 reformulated gasoline, 15% by volume of Petroleum benzine (PB), 10% by volume of ethanol, 5% by volume of 2,5-Dimethyltetrahydrofuran and 10% by volume of isopropyltoluene. Formulation 5-10 was tested to demonstrate how the invention enables the formulation of ethanol-containing gasoline with a low vapour pressure, wherein the presence in the motor fuel composition of ethanol does not induce an increase of dry vapour pressure equivalent in comparison to the source hydrocarbon component (HCC) . Moreo- ver, this gasoline secures a decrease of toxic emissions in the exhaust and a decrease of the fuel consumption in comparison with the above mixture RFM 5. The formulation 5-10 had the following specific properties: density at 15°C, according to ASTM D4052 764.6 kg /m3; initial boiling point, according to ASTM D 86 48.9°C; vaporisable portion - 70°C 25.3 % by volume; vaporisable portion - 100°C 50.8 % by volume; vaporisable portion - 150°C 76.5 % by volume; vaporisable portion - 190°C 95.6 % by volume; final boiling point 204.5°C; evaporation residue 1.4 % by volume; loss by evaporation 0.5 % by volume; oxygen content, according to ASTM D4815 4.6% w/w; acidity, according to ASTM D1613 weight% HAc 0.08; pH, according to ASTM D1287 7.5; sulfur content, according to ASTM D 5453 39 mg/kg; gum content, according to ASTM D381 1.5 mg/ 100ml; water content, according to ASTM D6304 0.1% w/w; aromatics, according to SS 155120, including benzene 38 % by volume; benzene alone, according to EN 238 0.4 % by volume; DVPE, according to ASTM D 5191 27.2 kPa; anti-knock index 0.5(RON+MON), according to ASTM D 2699-86 and ASTM D 2700-86 91.8 The motor fuel Formulation 5-10 was tested as described previously and gave the following results in comparison (+) or (-)% with the results for the motor fuel comprising 80 % by volume of reformulated A95 gasoline and 20 % by volume of Petroleum benzine: CO -12.3% HC -6.2%; NOx unchanged; C0 2 +2.6%; NMHC -6.4%; Fuel consumption, Fc, 1/ 100km +3.7% Similar results are obtained when other oxygen-containing additives of the invention substitute the oxygen-containing additives of the examples 5-1 to 5-10. To prepare all the above fuel formulations 5-1 to 5-10 of this motor fuel composition, initially the hydrocarbon component (HCC) which is a mixture of reformulated gasoline and Petroleum benzine (PB) was mixed with ethanol, to which mixture then was added the corresponding oxygen-containing additive and Cs-Ci2 hydrocarbons. The motor fuel composition obtained was then allowed to stand before testing between 1 and 24 hours at a temperature not lower than -35°C. All the above formulations were prepared without the use of any mixing devices. The invention demonstrated the possibility of adjusting the vapour pressure of the ethanol-containing motor fuels for the standard internal combustion spark ignition engines based on non-standard gasolines having a low vapour pressure. Figure 2 shows the behaviour of the dry vapour pressure equivalent (DVPE) when mixing the hydrocarbon component (HCC), comprising 80 % by volume of reformu- lated A92 gasoline and 20 % by volume of Petroleum benzine, with the oxygen- containing additive mixture 5, comprising 40 % by volume of ethanol, 20 % by volume of 3,3,5-trimethylcyclohexanone, and 20 % by volume of naphtha with boiling temperature 130-170°C and 20 % by volume of tert-butyltoluene. The graph demonstrates that the use of the additive of this invention enables obtaining ethanol- containing gasolines, the vapour pressure of which does not exceed the vapour pressure of the source hydrocarbon component (HCC). Similar DVPE behaviour was demonstrated when mixing the above oxygen- containing additive with hydrocarbon component (HCC) comprising 20 % by volume of Petroleum benzine (GC) and 80 % by volume of A95 or A98 reformulated gasoline. Similar results were obtained when other oxygen-containing compounds and Cs-Ci2 hydrocarbons of this invention were used in the proportion of the invention to for- mulate the oxygen- containing additive, which was then used for preparation of the ethanol-containing gasolines. These gasolines have a vapour pressure equivalent (DVPE) not higher than the DVPE of the source hydrocarbon component (HCC). At the same time the antiknock index for all ethanol-containing gasolines prepared in accordance with this invention was higher than that of the source hydrocarbon component (HCC) . The foregoing description and examples of preferred embodiments of this invention should be taken as illustrating, rather than as limiting, the present invention as defined by the claims. As will be readily appreciated, numerous variations and combinations of the features set forth above can be used without departing from the present invention as set forth in the claims. All such modifications are intended to be included within the scope of the following claims.

Claims: CLAIMS 1. Method of reducing the vapour pressure of a C 3 to C12 hydrocarbon-based motor fuel mixture containing 0.1 to 20 % by volume of ethanol for conventional spark ignition internal combustion engines, characterised in that, in addition to an ethanol component (b) and a C3 to C12 hydrocarbon component (a), an oxygen- containing additive (c) selected from at least one of the following types of compounds: alcohol, other than ethanol, ketone, ether, ester, hydroxyketone, ketone ester, and a heterocyclic compound containing oxygen, is used in the fuel mixture in an amount of at least 0.05 % by volume of the total fuel mixture. 2. Method of claim 1, characterised in that the oxygen- containing additive (c) is added to the ethanol component (b) which mixture of (c) and (b) is subsequently added to the hydrocarbon component (a) . 3. Method of claim 1, characterised in that the ethanol component (b) is added to the hydrocarbon component (a) to which mixture of (b) and (a) the oxygen- containing additive (c) is added. 4. Method of any of the previous claims, characterised in that the oxygen- containing additive is selected from the following compounds: an alkanol having from 3 to 10 carbon atoms, a ketone having from 4 to 9 carbon atoms, a dialkyl ether having from 6 to 10 carbon atoms, an alkyl ester of an alkanoic acid, said additive having 5 to 8 carbon atoms ,\ an hydroxyketone haying 4 to 6 carbon atoms, a ketone ester of an alkanoic acid, said additive having 5 to 8 carbon atoms, and an oxygen-containing heterocyclic compound having 5 to 8 carbon atoms. 5. Method of any of the previous claims, characterised in that the vapour pressure of the hydrocarbon based ethanol-containing fuel mixture is reduced by 50% of the ethanol-induced vapour pressure increase, more preferably by 80%, and even more preferably to a vapour pressure corresponding to that of the hydrocarbon component alone, and/or to the vapour pressure according to any standard requirement on commercially sold gasoline. 6. Method of any of the preceding claims, characterised in that the octane number of the thus-obtained fuel from (a), (b) and (c) is at least the same as that of (a) and /or meets the required standard limits for the octane number of commercially sold gasoline. 7. Method of any of the preceding claims, characterised in that the C 3 to C12 hydrocarbon mixture is selected from the group consisting of a non-reformulated, standard type of gasoline, a hydrocarbon liquid from petroleum refining, a hydrocarbon liquid from natural gas, a hydrocarbon liquid from an off-gas of chemical-recovery carbonisation, a hydrocarbon liquid from synthesis gas processing or mixtures thereof, with a non-reformulated, standard type of gasoline being preferred. 8 Method of any of the previous claims, characterised in that denatured ethanol mixture as it is supplied to the market, containing about 92% by volume of ethanol, and the remaining to 100% by volume part is hydrocarbons and by-products, can be used in the fuel composition or in the composition of the fuel additive. 9. The method of any of the previous claims characterised in that the ethanol component (b) used is at least about 99.5% ethanol by volume. 10. The method of any of the previous claims, characterised in that no means for mixing are used and the motor fuel composition is permitted to stand for at least one hour prior to use. 11. The method of any of the previous claims characterised in that the additive is used in amounts up to 15 % by volume of the total fuel composition. 12. The method of any of the previous claims, characterised in that the fuel composition obtained exhibits the following characteristics; (i) a density at 15°C, according to ASTM D 4059 of at least 690 kg /m- 3 ; (ii) an oxygen content according to ASTM D 4815 of no greater than 7% w/w; (iii) a dry vapour pressure equivalent according to ASTM D 5191 from 20 kPa to 120 kPa; (iv) an acids content according to ASTM D 1613 of no greater than 0.1 weight % HAc; (v) a pH according to ASTM D 1287 from 5 to 9; (vi) an aromatics content according to SS 155120 of no greater than 40 % by volume, wherein benzene is present in amounts according to EN 238 no greater than 1 % by volume; (vii) a sulfur content according to ASTM D 5453 of no greater than 50 mg/kg; (viii) a gum content according to ASTM D 381 of no greater than 2 mg/ 100 ml; (ix) a water content according to ASTM D6304 of no greater than 0.25% w/w; (x) distillation properties according to ASTM D86 wherein initial boiling point is at least 20°C; a vaporisable portion at 70°C is at least 25 % by volume; a vaporisable portion at 100°C is at least 50 % by volume; a vaporisable portion at 150°C is at least 75 % by volume; a vaporisable portion at 190°C is at least 95 % by volume; a final boiling point no greater than 205°C; and an evaporation residue no greater than 2 % by volume; and (xi) an anti-knock index 0.5 (RON+MON) according to ASTM D 2699-86 and ASTM D 2700-86 of at least 80. 13. A motor fuel composition for a conventional spark ignition internal combustion engine comprising: (a) a hydrocarbon component consisting of C3 - C12 hydrocarbon fractions; (b) a fuel grade ethanol present in amounts from 0.1% to 20%, suitably from 1 to 20%, preferably 3 to 15%, and more preferably 5 to 10 % by volume, based on the total volume of the motor fuel composition; and (c) an oxygen-containing additive comprising at least one of an alkanol having from 3 to 10 carbon atoms, a ketone having from 4 to 9 carbon atoms, a dialkyl ether having from 6 to 10 carbon atoms, an alkyl ester of an alkanoic acid, said additive having 5 to 8 carbon atoms, an hydroxyketone having 4 to 6 carbon atoms, a ketone ester of an alkanoic acid, said additive having 5 to 8 carbon atoms, and an oxygen-containing heterocyclic compound having 5 to 8 carbon atoms, said additive being present in amounts from 0.05% to 15%, suitably 0.1 to 15%, preferably 3 to 10%, and most preferably 5 to 10 % by volume based on the total volume of the motor fuel composition, obtainable by means of the method of any of the claims 1 to 12. 14. A mixture of fuel grade ethanol (b) and oxygen-containing additive (c) which can be used in the method of claim 1, characterised in having a ratio (b) to (c) of 1: 150 to 400: 1 by volume, more preferably from 1: 10 to 10: 1, and in the oxygen- containing additive being selected from an alkanol having from 3 to 10 carbon atoms, a ketone having from 4 to 9 carbon atoms, a dialkyl ether having from 6 to 10 carbon atoms, an alkyl ester of an alkanoic acid, said additive having 5 to 8 carbon atoms, an hydroxyketone having 4 to 6 carbon atoms, a ketone ester of an alkanoic acid, said additive having 5 to 8 carbon atoms, and an oxygen- containing heterocy- clic compound having 5 to 8 carbon atoms. 15. The mixture of claim 14, characterised in comprising the ethanol component (b) in the amount of 0.5-99.5%, preferably from 9.5 up to 99%, more preferably from 20 up to 95 % by volume, and most preferably from 25 up to 92 % by volume; the oxygen-containing component (c) in an amount of 0.5 - 99.5%, preferably from 0.5% up to 90%, more preferably from 0.5 up to 80%, and most preferably from 3 up to 70 % by volume; and component (d) comprising at least one Cβ - C12 hydrocarbon, preferably Cs-Cπ hydrocarbon, in an amount from 0 up to 99%, preferably from 0 up to 90%, more preferably from 0 up to 79.5%, and most preferably from 5 up to 77 % by volume, the ratio between the components in the mixture (b):((c) + (d)) preferably being maintained within the limits from 1:200 up to 200: 1, more preferably from 1: 10 to 10: 1. 16. The mixture of claim 15, characterised in that the component (d) is an individ- ual aliphatic saturated and unsaturated, or alicyclic saturated or unsaturated hydrocarbon, or mixtures thereof, and/ or a fraction of hydrocarbons boiling at 100- 200°C, obtained in distillation of oil, bituminous coal resin, or products yielded from processing of synthesis-gas. 17. The mixture of claims 14 - 16, charecterised in that the component (b) is denatured ethanol mixture as it is supplied to the market, containing about 92% by volume of ethanol, and the remaining to 100% by volume part of the component (b) is hydrocarbons and by-products. 18. The mixture of claims 14 - 16, charecterised in that the fuel grade ethanol contains at least 99.5% by volume of ethanol. 19. Use of the mixture of claims 14 - 16 as a fuel in a modified gasoline engine. 20. Use of the mixture of claims 14 - 16 for obtaining an ethanol-containing gasoline fuel and adjusting the octane number of such a fuel to a desired level by mixing a corresponding amount of said mixture with a conventional gasoline fuel (a), while maintaining or decreasing the vapour pressure of the thus-obtained fuel composi- tion as compared to the vapour pressure of the gasoline component (a) alone.

Inventors: GOLUBKOV ANGELICA, GOLUBKOV IGOR, GOLUBKOV, ANGELICA, GOLUBKOV, IGOR
Applicants: GOLUBKOV ANGELICA, GOLUBKOV IGOR, GOLUBKOV, ANGELICA, GOLUBKOV, IGOR
Application year: 2001
Main classification: C10L1
IPC codes: C10L1, C10L10