jhawkr

Oh, one other thing. Ask any gas station manager/owner and he'll tell you he sells a lot more 87 than anything else and it is usually fresher as a result.

TheDivaDanielle

you can run what you want in these cars. you can run as low as 87 octane. It'll be down a little bit of power, that's about it.

cedarmn

I would agree, run what you want. If you are planning on driving your car hard you may want the better gas. Other than that I would assume if you run at high elevations all the time your car would want the higher Octane. I also ready in one of the sticky posts that someone did a comparison on 87 vs 91 and they actually got enough milege gains that it was cheaper running 91. I also think they used a tuner to maximize the milege.

RetiredSFC 97

I read that as well. It's because 91, in some states don't have ethanol and ethanol burns faster with less mileage than non ethanol does. That's what people keep forgetting in their research and articles and opinions. It's also another reason to stay the hell away from 87 octane.

jhawkr

I see the ethanol argument as a myth. It was true long ago when hoses disintegrated when exposed to alcohol and there were other adverse effects. All cars are designed now to be compatible with 10% ethanol. Some, like Flex Fuel models, can use 15% safely. The stations around here that sell ethanol free 91 (BP), charge about .10 more per gal than 91 with ethanol so it is unlikely to be cost effective. I used a tankful once and watched my computer mileage drop about .5 mpg. (That was in my 2010 GT)

If I were to go to the track or if I was involved in street racing, I would definitely use 91 or 93 octane. I'd probably also be adding performance enhancements and spending wads of money on the next latest thing. But, from the factory, even with 87 octane, a 3600 lb car with over 400 hp is a LOT of hp/lb.