this is a performance vehicle. usually requires premium fuel. higher octane reduces knocking in these types of engines. if you are using 87 to save money, than i would upgrade air intake to a cold air intake system(K&N) to offset the lower octane fuel. i would also sue fuel additives(specifically ethanol treatment) to clean fuel system. ethanol leaves residue build up that can cause the knocking sound. premium spark plugs and performance grade ignition cables or coils(accel's are good and cheaper than OEM replacements). over all these slight modifications will help overall performance and fuel economy. these are the things i have done for my own ride. 300,000 kil. and still kicking ass.