thehangman

a couple months ago I purchased a 2001 2.8l A4 quattro. I absolutely love it.
when i was initially investigating the A4, The fuel economy was one thing i had to get over. its not a matter of fuel cost, simply my green side trying to balance out my desire for a smooth car that has some power to spare if i need it.

so 18city 24highway is something i rationalized.

however, after having the car for a few months and keeping track of the fuel, its getting more like 14mi/gal.

my first tank was actually more like 13, but I inflated my tires to the correct psi, and gained a little.

Also, I should be clear that i am not an aggressive driver, i drive quite conservatively. I've consciously driven even more so just to see how that might effect the fuel economy with no change.

a friend suggested that it could be the Fuel injectors getting a little gummed up. i was going to put some fuel injector cleaner in the next tank of gas, but does that stuff even work?

any other suggestions would be much appreciated.

-steve

4Driver4

Any codes? How old are the O2 sensors? Air filter? Plugs?

brothers

I've got an '00 2.8 A4 Avant (5 speed manual). I consistently get 20 MPG in mixed highway/around town driving, and I'm not a particularly conservative driver.

- Dennis

hellbringer

in addition to 4driver4's questions. ..what's the mileage on your ride? Also what's your city/highway breakdown?

turbo510

You should easily get 26 on the highway. I just filled up my '96 2.8, average for the tank was just under 26 MPG, which was mostly highway, often at 80, but some stop and go. Mine's also an automatic.

Besides the engine, draging brakes, alignment, or just high-rolling resistance tires could ruin your mileage. Try putting it in neutral at highway speed and notice how well it coasts, you could do this next to a friend in another car to see how they compare.

Try Techron fuel system cleaner, Audi used to recommend it for earlier models. I also like to use 5W-30 synthetic for less engine friction. As mentioned the O2 sensors (pre-cats) and the MAF have to be working properly too.

thehangman

The car is an automatic and has 106,000 miles on it. the 14MPG I"m getting is mixed. my drive to work is probably 5 miles each way. and its probably a 50/50 split highway and city.
the car estimates that i get 24ish on the freeway stretch, and like 12-14ish city.

i have most of the service records for the car. At 83K the sparkplugs and air filter were done. That is the last record of those being done that I see.

So I will definitely be checking, and very likely replacing the air filter.

I was planning on ordering a code reader, just havent gotten around to it.
this may sound like a pretty green question but would I get a check engine light if there were codes? or can there be codes without the check engine light?


thanks everyone for your help!

hellbringer

I've been on this kick changing all my diff gear oil. .on my 98 B5 2.8 with 98k. My MPG increased 5mpg Highway just by changing all the diff fluids. Now my brakes are getting a workout cause my car just rolls! =)

Below is a little write-up and a pic of pebbles in my diff gear oil!
https://www.audiworld.com/forums/sho...ht=center+diff

turbo510

How quickly does your car get up to normal temperature? thermostats can wear out and stick open, keeping the fuel injection in warm-up mode. Coolant temp sensors are also known to fail, which can make the engine run rich even if the coolant is at the correct temp. Besides that, your 5-mile commute is going require more gas just because the engine is below operating temperature for a good part of the trip. So, under these conditions, maybe your mileage is normal!

A code reader will be worth the cost the first time it helps solve a problem on your car. Yes, there can be codes that don't trigger the CEL. Before one of my oxygen sensors quit working, I would get a "slow response" code that didn't turn on the CEL.

Regarding the air filter, I for one can't see how a dirty filter could affect gas mileage, since it is just another restriction in series with the variable restriction (throttle). The MAF and O2 sensors will still adjust the fuel usage.

RobQ

I have the same year car, 5 spd. I routinely get 25-26 mpg, mixed between highway and town.

thehangman

I do let it run a bit before I drive off. if i let it run for about five minutes, and then start driving. its not at prime operating temperature but it certainly isn't cold. is there a way to test the coolant temp sensor with a multi meter?

I think I'll order a code reader. anything in particular I should look for in a code reader?