slimsol

I have used regular 87 octane for last couple of fill ups. I noticed few things with regular gas
- Better off line acceleration
- Car revs freely
- Upshifting at ~2200 rpm during normal acceleration
- Better throttle response while highway driving
- Lesser gas mileage
Premium gas
- Car doesnt seem to rev as fast
- Better low end torque
- Upshifting ~1800 rpm
- Way better gas mileage ~50 miles per tank
- throttle reponse is less. Have to push gas pedal harder in order to pass on highway

Have you guys observed this? Any idea why car would rev so quickly with regular gas but have poor gas mileage?

findalex

The higher octane of "premium" gas prevents pinging (early ignition) and damage to a turbo-charged engine. "Premium" is a misnomer. It's just a gas station marketing gimmick. It's nothing more than an octane rating, like 5W-30 and 15W-40 for motor oil. One is no better than the other. Each is ideal for the engine designed to use it.

When you put a lower octane engine, the computer senses the pinging and changes the ignition timing/fuel injection/valve timing to minimize damage. On the other hand, the higher octane gas has less energy density than the lower octane gas. So what you are seeing is the effect of the computer compensating for the lower octane gas's early detonation.

If you want your engine to perform to its full potential, please do not use lower octane gas.