A gasoline composition for use in a spark-ignition engine, comprising: (a) a major amount of a gasoline base fluid; (b) in the range of from 10 to 1,500 ppmw of a polysubstituted alkanol amine derivative reaction product obtainable by reacting in a thermal condensation reaction: (i) a carboxylate compound of formula I R 1 COOR 2 in which: R 1 is an aliphatic C 1-30 -hydrocarbon radical; and R 2 is hydrogen or alkyl, mono- or polyhydroxyalkyl, or ammonium; with (ii) an alkanol amine of the formula II NHR 3 R 4 wherein R 3 and R 4 are independently selected from hydrogen atoms and linear or branched-chain hydrocarbon groups, the carbon chain of which is optionally interrupted by one or more -NH- groups and which optionally has at least one hydroxyl group attached to a carbon atom of the hydrocarbon group, with the proviso that R 3 and R 4 are not both hydrogen atoms and that at least one of said residues R 3 and R 4 carries at least one hydroxyl group; in a molar ratio of the -COO- groups of the carboxylate compound of formula I to the molar sum of OH and NH groups of the alkanol amine of formula II in the range of from 1.8:3 to 3:3; and (c) in the range of from 10 to 5,000 ppmw of a detergent additive which is a polyalkylene monoamine, the polyakylene radical having a number average molecular weight in the range of from 300 to 5000. (a) a major amount of a gasoline base fluid; (b) in the range of from 10 to 1,500 ppmw of a polysubstituted alkanol amine derivative reaction product obtainable by reacting in a thermal condensation reaction: (i) a carboxylate compound of formula I R 1 COOR 2 in which: R 1 is an aliphatic C 1-30 -hydrocarbon radical; and R 2 is hydrogen or alkyl, mono- or polyhydroxyalkyl, or ammonium; with (ii) an alkanol amine of the formula II NHR 3 R 4 wherein R 3 and R 4 are independently selected from hydrogen atoms and linear or branched-chain hydrocarbon groups, the carbon chain of which is optionally interrupted by one or more -NH- groups and which optionally has at least one hydroxyl group attached to a carbon atom of the hydrocarbon group, with the proviso that R 3 and R 4 are not both hydrogen atoms and that at least one of said residues R 3 and R 4 carries at least one hydroxyl group; in a molar ratio of the -COO- groups of the carboxylate compound of formula I to the molar sum of OH and NH groups of the alkanol amine of formula II in the range of from 1.8:3 to 3:3; and (i) a carboxylate compound of formula I R 1 COOR 2 in which: R 1 is an aliphatic C 1-30 -hydrocarbon radical; and R 2 is hydrogen or alkyl, mono- or polyhydroxyalkyl, or ammonium; with R 1 is an aliphatic C 1-30 -hydrocarbon radical; and R 2 is hydrogen or alkyl, mono- or polyhydroxyalkyl, or ammonium; with (ii) an alkanol amine of the formula II NHR 3 R 4 wherein R 3 and R 4 are independently selected from hydrogen atoms and linear or branched-chain hydrocarbon groups, the carbon chain of which is optionally interrupted by one or more -NH- groups and which optionally has at least one hydroxyl group attached to a carbon atom of the hydrocarbon group, with the proviso that R 3 and R 4 are not both hydrogen atoms and that at least one of said residues R 3 and R 4 carries at least one hydroxyl group; (c) in the range of from 10 to 5,000 ppmw of a detergent additive which is a polyalkylene monoamine, the polyakylene radical having a number average molecular weight in the range of from 300 to 5000.