The Saab 95 Aero in 99 had a variable compression engine that is capable of adjusting from 7:1 to 14:1 by adjusting the pitch of the head against the block. It does this to adjust to varying road conditions, but will also do it based on the fuel it's burning... so, no... it won't hurt THAT car, but it will run a heck of a lot better with 93 octane, and make more power. Not all turbo cars are like that. Most say "Premium Unleaded Fuel Only" right on the speedometer or under the gas tank door.