Found this article in my February '08 Popular Mechanics.
Question asked - I own a supercharged '92 Buick Park Avenue Ultra that I bought about four years ago. The manual says to use premium gasoline, but the dealer says they NEVER put premium in these cars, and it isn't necessary if the engine doesn't ping. Do you agree?
Popular Mechanics answer - Not exactly. With the supercharger, there is enough cylinder pressure at WOT to cause detonation using low octane gas. Your engine, like virtually all modern fuel injected engines, has a knock sensor. It'* a small microphone bolted to the cylinder head that listens for the first sign of engine knocking and signals the fuel injection computer when it occurs. The engine computer then retards the ignition timing and enriches the fuel/air mixture to prevent knocking. This keeps the detonation from melting holes in the tops of your pistons, which will pretty much destroy the engine. When the car'* computer rolls back the timing engine performance and economy are substantially reduced. You bought a supercharged car expecting a certain level of performance, and you won't get it running cheap gas. Moreover, the reduced fuel economy on regular will offset much of the savings from using lower-grade fuel.
Nice answer Popular Mechanics.
I hate when dealers say it'* ok to put regular in a car that REQUIRES premium.