An unleaded aviation fuel composition having a MON of at least 99.6, sulfur content of less than 0.05wt%, a T10 of at most 75°C, T40 of at least 75°C, a T50 of at most 105°C, a T90 of at most 135°C, a final boiling point of less than 190°C, an adjusted heat of combustion of at least 43.5 MJ/kg, a vapor pressure in the range of 38 to 49 kPa, comprising from 5 vol.% to 20 vol.% of toluene having a MON of at least 107; from 2 vol.% to 10 vol.% of aniline; from 35 vol.% to 65 vol.% of at least one alkylate or alkylate blend having an initial boiling range of from 32°C to 60°C and a final boiling range of from 105°C to 140°C, having T40 of less than 99°C, T50 of less than 100°C, T90 of less than 110°C, the alkylate or alkylate blend comprising isoparaffins from 4 to 9 carbon atoms, 3-20 vol.% of C5 isoparaffins, 3-15 vol.% of C7 isoparaffins, and 60-90 vol.% of C8 isoparaffins, based on the alkylate or alkylate blend, and less than 1 vol.% of C10+, based on the alkylate or alkylate blend; from 5 vol.% to 20 vol.% of a diethyl carbonate with the proviso that the combined toluene and diethyl carbonate content less aniline content is greater than 20vol%; and at least 8 vol.% of isopentane in an amount sufficient to reach a vapor pressure in the range of 38 to 49 kPa; wherein the fuel composition contains less than 1 vol.% of C8 aromatics, and wherein the adjusted heat of combustion is calculated as follows: HOC * = HOC V / density + % range increase % payload increase + 1 where HOC* is the adjusted Heat of Combustion (MJ/kg), HOC V is the volumetric energy density (MJ/L) obtained from actual Heat of Combustion measurement, density is the fuel density (g/L), % range increase is the percentage increase in aircraft range compared to 100 LL(HOC LL) calculated using HOC V and HOC LL for a fixed fuel volume, and % payload increase is the corresponding percentage increase in payload capacity due to the mass of the fuel. from 5 vol.% to 20 vol.% of toluene having a MON of at least 107; from 2 vol.% to 10 vol.% of aniline; from 35 vol.% to 65 vol.% of at least one alkylate or alkylate blend having an initial boiling range of from 32°C to 60°C and a final boiling range of from 105°C to 140°C, having T40 of less than 99°C, T50 of less than 100°C, T90 of less than 110°C, the alkylate or alkylate blend comprising isoparaffins from 4 to 9 carbon atoms, 3-20 vol.% of C5 isoparaffins, 3-15 vol.% of C7 isoparaffins, and 60-90 vol.% of C8 isoparaffins, based on the alkylate or alkylate blend, and less than 1 vol.% of C10+, based on the alkylate or alkylate blend; from 5 vol.% to 20 vol.% of a diethyl carbonate with the proviso that the combined toluene and diethyl carbonate content less aniline content is greater than 20vol%; and at least 8 vol.% of isopentane in an amount sufficient to reach a vapor pressure in the range of 38 to 49 kPa; where HOC* is the adjusted Heat of Combustion (MJ/kg), HOC V is the volumetric energy density (MJ/L) obtained from actual Heat of Combustion measurement, density is the fuel density (g/L), % range increase is the percentage increase in aircraft range compared to 100 LL(HOC LL) calculated using HOC V and HOC LL for a fixed fuel volume, and % payload increase is the corresponding percentage increase in payload capacity due to the mass of the fuel.