Since the beginning of January, I've been getting horrible gas mileage. Prior I would get about 400 miles per tank, whereas now I'm barely scratching 300.
Possibilities? Things to check? Colder weather have anything to do with it?

Car is a '86 5000 CS turbo quattro, 21.1 gallon tank.

Thanks.

 

Is it just reduced gas mileage? Do you notice any thing else not normal?

I've got a 86 5000 cs turbo also, and a couple months back was also getting bad mileage all of a sudden. The car was also idling rough, tinkered around with the air/fuel mixture adjustment screw until idle felt good and gas mileage went back to normal.

Clean air filter?
Fuel filter?
Oxygen sensor?

 

It cranks for twice the time it used to before it finally starts, but besides that the engine runs normally. I thought that the increased starting time may be from the cold though.