Only 91+. It is a high-compression, turbocharged engine - it would likely kill the boost and retard the ignition if it ever heard detonation.
Yikes. Around my area, the difference between regular and premium is usually $1/gallon. I get the "if you can afford the 70k car you can afford the fuel" comments people always make, but man, its steep. In the Chicago area, we are talking ~$4 vs ~$5/gallon. i haven't put premium in anything that asks for it for years without any issues, but I don't have any turbos, I have the disco and Lexus/Toyota V6's that ask for different octane in different cars and model years. I maybe notice 1-2 mpg hit, maybe, but that is definately not worth $1 for that difference.
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