I had a quick question on a 2001 Audi A4 Quattro, 1.8t, automatic transmission. The on-car display is saying the car averages around 18 mpg. This seems poor, especially considering my dad has a full size 4 x4 Ford Expedition with a 5.4L V8 that averages around 15 mpg.

Is this fuel economy normal, or should I look at doing a good tuneup, such as replacing the o2 sensor?

 

how many miles? City or highway driving?

 

18 mpg doesn't seem right. I get ~25 mpg in the summer with lots of mods and moderate/hard driving.

 

The car has about 70k miles, and I do mainly city driving with a little freeway, but I did a similar type of driving when I borrowed by dad's Suv, so it's a pretty good comparison. 18 miles a gallon is ridiculous for a modern 4 cylinder compact sedan, so I'm guessing it's time for a new o2 sensor, since to my knowledge it's never been replaced.

 

The o2 sensor is a possibility, but only do the pre-cat o2 sensor. The post-cat sensor only checks emissions and has no effect on gas mileage.

 

maybe in the city it's 18, but highway should be 25-27 stock

 

ya man i would get that checked.. my 2.8 gets about 24 in the city and 28 on the highway.

 

Could be a bad precat oxygen sensor. When is the last time you changed the spark plugs and air filter?

Check for codes with a code reader and check them here.

I have never been as low as 18 mpg.

 

CTS

 

Last time I figured mine out I got 26 Highway and 15 city.