Patent ID: 7052597

Claim:
A plurality of fuels comprising: at least a first unleaded fuel and a second unleaded fuel, each boiling in the gasoline range and operable in a spark ignition, internal combustion engine having a compression ratio, CR, of 11 or more, the first fuel being a mixture of hydrocarbons with greater than 45 vol % aromatics and having a research octane number, RON, greater than 100, and at high load conditions an average burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane; the second fuel being a mixture of hydrocarbons having a research octane number, RON, less than 90, and at low load conditions a burn rate greater than 105% of isooctane and a laminar flame speed greater than 105% of isooctane and containing less than 45 vol % aromatics.