[salannelson]

This probably isnt going to be answered but I'm gonna give it a shot..

I'm looking at a real nice 02 Pontiac Grand Prix GTP (Supercharged), and I read online in a few places that it takes premium gas? Is this true? If it is, how would it run on reg?

 

[zx10guy]

Don't cheapen out. The GTP's engine is meant to be a performance engine. The very nature of the engine being supercharged requires premium gas to prevent detonation. Not only can/will engine performance suffer, you are risking possible engine damage.

If you are are at the margins where you can't afford to pay for premium gas at every fill up, you're better off skipping this car and finding a car which will take regular octane.

 

[Uncle Erik]

IIRC, the Car Guys tackled this question some time back. They said that the engine computer can handle lower octanes, but that you won't get the last bit of performance from it. If you're just driving around town, regular should be OK. If you want to do some spirited driving, then fill up with premium.

 

[zx10guy]

Here's the problem with letting the ECM deal with lower octane fuel. Computer controlled engines detect engine knock via a knock sensor. The knock sensor is a microphone which is tuned to produce a signal when it detects detonation. The problem with this situation is the knock sensor has to be sensitive enough to pick up on the beginnings of detonation. The other problem is that when the knock sensor triggers, this means your engine is already knocking.

So I still stand by my statement. If you're that close to the margins where you have to skimp on not using the proper fuel, then you're better off buying a car which doesn't require premium. But in the end, it's your money.