Bad gas mileage these past two weeks?
 

I have a 2009 Audi A6 Avant with the 3.0T engine. In Boston, I used to get 11-13mpg in the city and 26-27 on the highway. Now I'm getting 8-9 city and 23-24 highway. Any ideas what could be wrong? I am having my spark plugs changed next week. I have 80k miles on the car. I'm a bit worried...

Thanks!

It has been really cold and you have been driving on snow covered roads. That makes a difference

Also when was the last time you replaced that fuel filter? Plus will make a difference no doubt. And consider the maf as a tertiary possible root

Still getting terrible gas mileage... haven't gotten about 21 mpg on the highway, as before I was getting 25-26mpg. and it's been warm these past few weeks (sans the last three days)...

i haven't replaced the fuel filter. is that the same thing as the air filter? should i replace both?

what is a MAF?

thanks!

EDIT: It looks like I may have changed the fuel filter about a year ago. Should I replace it again?

No if the fuel filter was replaced one year ago.

As for your increased fuel consumption. Check all your vacuum hoses for leaks. Vacuum hoses become brittle with time and constant exposure to the engine heat. Then in really cold weather the hose breaks.