Aromatic solvents are often found in antiknock additives and octane boosters. They are used as antiknock additives/octane boosters which increase gasoline octane and reduce engine 'pinging' (detonation or pre-ignition).
Our solvents have no adverse effects such as health effects or effects on the engine that burns them. Toluene and xylene are the main aromatic organic solvents often found in antiknock additives. They are both octane boosters, present in crude oil and present at increased concentrations in refined gasoline. Neither has been shown to be carcinogenic, so both are candidates for use and in fact are two solvents often found in antiknock additives.