I have a hard time believing that it does. If you turn on the a/c then yeah, but using just regular electronics in the car like that should not affect your gas mileage at all. If it does it would be MARGINAL at best...

 

The radio shouldn't affect mileage since it uses little power. Heated seats, a little more. Heat, AC, blower, rear defroster, even more. Headlights too, they're on more in the winter. Wipers, etc. It all adds up. But the biggest cause is the short city trips, stop and go, and the cold weather.

 

my 2.8 is pure **** on gas i am luky if i get 300 kms per tank not miles it sucks filling her up all the time but i love her so i get ER done lol haha

 

I also have the avant 2.6 and its shocking on fuel but its a nice car and does what I want it for, nothing will compare to my XK120 Jaguar but I have leather gloves which have the rings on them which means im a proud owner of the Audi

 

well I just took my car on a road trip and I got 26mpg on the expressway/highways... so I guess I just really underestimated the amount it would drop in the city with the short trips. Never lived in a city before so I had no idea. Thanks all for your suggestions.

 

How old are your pre-cat oxygen sensors?
Mileage is worse in winter, short trips, and winter fuel and if you go to a place that uses 10% ethanol in their gas.