Premium Gas

[WRBlue]

Originally Posted by Black Yaris

so the higher octane combined with vvt-i will not change fuel econ?

Yes. Why would it?

[cleong]

Originally Posted by WRBlue

Yes. Why would it?

Wouldn't a higher octane allow the engine to increase its timing and make more power, which means that less fuel is needed to maintain a given speed?

[Yarii]

Engine's don't detect the octane of fuel... They just retard the timing if they detect knocking. Without doing some ECU tuning, the timing will always be set to or below (if knocking is present) whatever toyota engineers pre-programmed it to be based on engine and air conditions.

Premium might help keep the timing from retarding under high engine load like heavy acceleration or towing/hill climbing when knocking might occur, but for most daily driving, the engine will use the same timing settings it uses on regular gas.

Originally Posted by cleong

Wouldn't a higher octane allow the engine to increase its timing and make more power, which means that less fuel is needed to maintain a given speed?