I have a 2003 Sedan and I was wondering if running 91 octane gas would be of any benefit for me? I read that it can help in the long run but where I live its quite a bit more expensive to put that gas in your tank... Thanks!

 

The vehicle was designed to run on premium, however you can put in lower octane fuel and the ECU will compensate for it. The most important thing is to use "top tier" fuel, the detergent additives will keep the pump/injectors/valves/pistons CLEANER than "trash-gas". A top tier fueling station usually displays it at the pump.

Something else to consider about octane, it takes slightly MORE fuel to move the same distance at a lower octane, for me it's a difference of roughly 30 miles per tank (napkin math from the last year), my average tank lasts 330 miles so I see a loss of roughly -10% distance by running 87 octane. The difference in fuel cost between 87 and 91 is roughly +10%, about 25cents more per gallon so it's literally almost the EXACT SAME COST for me to run regular or premium, but I have fewer trips to the fueling station over the course of a year because I can drive 10% further.

Plus my engine isnt riding the knock sensor so hard when I'm gunning down the highway in the middle of 110 degree summer heat, and the engine is more responsive when I push the right foot pedal to the floor.