I checked the screen by the speedometer and it said i get about 15 mpg!!

OMG why is it so bad? I have a 2000 2.8 quattro. I thought they did about 22-24

 

Dirty air filters, alignment, brake drag, tire pressure, fuel filters, mass air flow sensors, fuel injectors timing problems, engine temp, type of gas used,style of driving,average speeds, idle timeand accessories used all affect gas mileage. Keep in mind the factory estimate is for closed course driving in perfect conditions which is almost impossible in normal driving conditions.

 

I wouldn't rely on the trip computer to be totally accurate. I would fill up the tank, reset the odometer, drive until empty, refill, take the total miles driven (from odometer) divide that by the total amount of gas (gallons) needed to refill the tank.

 

My 2000 2.8 Quatro Avant will cruise at about 70-75 on flat ground with a readout of about 22-26 MPG depending on wind and load in the car.

 

mine runs 21 average

 

I get about 22 on average, but drive 75% on the hwy. Let off the gas a bit and I'm sure it will go up. You are probably putting a lot of short trips on the car going to and from school in city. My in city milage is about 15mpg. I also drive my wagon like a grandpa.

 

Try not to step hard on the gas when you are ona stop light, just accelerate slowly, and plan ahead on your trip. Best thing also is buy a PRIUS (lol) j/k. Put some K&N filter in there I have it on mine and no problem at all.

 

the thing is that sometimes i go without accelerating real fast at ever light

i tried driving like a grandpa

also for some reason, like you know were it reads how many miles you can drive on gas u have, well mine goes up and down constantly. Like ill fill up, itll say 300, then go down to 250, then go up to 350, keeps doing that. If i have like 100, itll go down to 70, go up to like 150, etc.. u get the point. Also the display of fuel in the car shifts up and down constantly, like itll be at half, then itll go down and up...

is something wrong with the sensors?

Also i dont know if this is a problem, but this doesnt happen on any other cars ive driven. If im driving and i have my foot on the gas and i take my foot off, the car slows down instead of just coasting...

 

Hmm that sounds kinda like you might have something going on with the fuel level sensor in the tank or possibly one of the connections to it. I have never seen my fuel Gage fluctuate much at all. I assume the trip computer uses the tank sensor in some way to set the number of miles you have to go until you need to refill. I assume this is in conjunction with what the other fuel consumption sensor's or maybe its just based on preset numbers based on throttle position and so on. At any rate I bet if there is a problem with the in tank sensor it will show up also in the readouts on the dash. Just a guess but it might be something to check out.

 

when the mileage estimate goes up and down its because its estimating how long you can go by the way you're driving. if you are driving slow and fast and slow and fast and accelerating alot then the distance you can go on a certian amount of gas will be shorter than if you're steadily crusing on the highway. I drive a 98 as well, the people at the audi dealership i work at have told me its common small stuff like that happens in that car because it was the first production year of that version so there were still some bugs in it.