Re: What fuel do you use?
Interesting reading...or ranting...or both. Somewhat educational, too. My Audis also call for 91 octane. Yes, the computer can adjust for lower octane but it does affect performance while not seeming to impact gas mileage. I either fill them with premium 91 or 93, depending on what is available, or I alternate 1/2 tanks of mid-range and premium. I've been doing this on an A6 with 235k miles and she's still driving strong although the body is starting to go, but that's not due to octane. I do NOT use regular, 87 octane ever.