Can you use 85 instead of 91 premium gasoline in 2000 Audi s4?

I have Audi S4 . The gas prices are just too much. If i start putting regular 85, will it plug up any of my systems of damage any valves?Can you use 85 instead of 91 premium gasoline in 2000 Audi s4?no thats not the problem that extra 20 cents does not add up that fast, you need to learn some math, it takes 20 gallons before it adds up to one gallon that means if you saved that 20 cents thats one gallon of gas you are not getting. so changing to regular will destroy a high compression engine, you want to risk an engine for a gallon of gas every tank? I dont think so. toyota run on regular you can buy one of those?Can you use 85 instead of 91 premium gasoline in 2000 Audi s4?NO! If you cannot afford the gas for a car like this you should not be owning/driving one. This is a twin turbo car, and turbo cars take premium along with any non forced aspirated high compression engines. This car will wreck havoc if you put anything lower than 91 octane in it.Can you use 85 instead of 91 premium gasoline in 2000 Audi s4?Look in the manual... If it says to use 91, then use it! If you put 85 in a car that needs 91 you're going to have serious engine issues.