98a6quattro

which gas do you guys use in your Q? I always put Premium, but today i was looking through the owners manual and it states Regular is ok. Considering i've been getting about 16mpg, Regular might not be a bad idea.

AutoUnionQ7

Unless you want to get even worse mileage, I'd stick with Prem. The extra detergents and additive packs used for the higher grade is alone worth all the extra money. Especially on these direct injection FSI engines

kaptom540

well the 4.2 requires at least 91 octane .. I would double check the inside of the gas fill area .. should state the octane requirement .. if you can get away using regular .. i would suggest using premium every 4th fill up ..

Jusforfun

There have already been a few threads on this topic. The car compensates for lower grade or lower octane fuels resulting in slightly reduced power. The general opinion is it has to work harder to compensate which eats up most of your saving.
Engine wear can be increased and service intervals decreased. All in all its not worth it.