Poor fuel mileage on my 2000 A8 Quattro
09-17-2017, 06:35 PM
#1
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Poor fuel mileage on my 2000 A8 Quattro
I drive 28 miles on a divided highway at 60 mph, and thee miles in town. I drive conservatively and the fuel mileage is bad, getting an average of 14 mpg.
No check engine light is on.
Mileage is 108,000.
When coasting, the car slows down more than I think it should. But it is an AWD, so that could be it.
Any help about this would be appreciated.
No check engine light is on.
Mileage is 108,000.
When coasting, the car slows down more than I think it should. But it is an AWD, so that could be it.
Any help about this would be appreciated.
09-18-2017, 07:09 AM
#2
AudiWorld Member
If it has been longer than you can remember since your last tune-up.. maybe it's time.
Air Filter could be causing the problem. Have there been any fuel conditioners used lately? Intake/throttle body cleaner?
Try driving the speed limit. 60 mph is putting around..
For reference, I get 18/21 in town and 22/24 mpg on the road.
Check tire pressures too. pc
Air Filter could be causing the problem. Have there been any fuel conditioners used lately? Intake/throttle body cleaner?
Try driving the speed limit. 60 mph is putting around..
For reference, I get 18/21 in town and 22/24 mpg on the road.
Check tire pressures too. pc
09-18-2017, 02:48 PM
#4
AudiWorld Senior Member
I'm getting 16.6 mpg. 17 miles of mixed city and highway daily driving. Premium gas (non-ethanol), tires 32 psi cold start, air filter, fuel filter, spark plugs and all four o2 sensors are relatively new.
You could check for a brake dragging on the slowing issue.
Good luck.
You could check for a brake dragging on the slowing issue.
Good luck.
Last edited by 2001 S8; 09-18-2017 at 02:51 PM.
09-18-2017, 03:31 PM
#5
In my 2001 A8 I get 19MPG in mixed driving, 25ish on highway trips. You could check for hot brakes (carefully) as maybe one is dragging. I used to get slightly better MPG, at 175K miles now. Maybe I should clean the MAF. My O2 sensors should not need replacing just yet.
Computer-based tests might help, airflow at the MAF and the O2 sensor tests, cat temp and readiness. You could also double check your MPG manually and also check your odometer, you did not say how you were doing it now. The air filter is a good thought, might have a big mouse nest in there.
In my S8 I get 17ish, better on highway trips.
Computer-based tests might help, airflow at the MAF and the O2 sensor tests, cat temp and readiness. You could also double check your MPG manually and also check your odometer, you did not say how you were doing it now. The air filter is a good thought, might have a big mouse nest in there.
In my S8 I get 17ish, better on highway trips.
09-19-2017, 08:21 AM
#6
AudiWorld Member
In my 2001 A8 I get 19MPG in mixed driving, 25ish on highway trips. You could check for hot brakes (carefully) as maybe one is dragging. I used to get slightly better MPG, at 175K miles now. Maybe I should clean the MAF. My O2 sensors should not need replacing just yet.
The typical gas used in these Audi's is CRAP. A good fuel additive with a fill-up (in my case, is a no brainer.) The difference in milage more than covers the cost of the additive.
Go on-line to find it by the case..
Computer-based tests might help, airflow at the MAF and the O2 sensor tests, cat temp and readiness. You could also double check your MPG manually and also check your odometer, you did not say how you were doing it now. The air filter is a good thought, might have a big mouse nest in there.
In my S8 I get 17ish, better on highway trips.
The typical gas used in these Audi's is CRAP. A good fuel additive with a fill-up (in my case, is a no brainer.) The difference in milage more than covers the cost of the additive.
Go on-line to find it by the case..
Computer-based tests might help, airflow at the MAF and the O2 sensor tests, cat temp and readiness. You could also double check your MPG manually and also check your odometer, you did not say how you were doing it now. The air filter is a good thought, might have a big mouse nest in there.
In my S8 I get 17ish, better on highway trips.
I tend to replace mine every 75k or so FWIW (Parts Geek.)
09-19-2017, 09:06 AM
#7
The O2 sensors all looked good in the VCDS tests recently, they have less than 75K on them. I might dunk them in the ultrasonic cleaner for a while next time I am under the car.
For the OP, if there is uncertainty about the state of the O2 sensors IMO they should be replaced. They can cause poor mileage and also the rich-running is hard on the cats. Cats cost more than O2 sensors.
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09-19-2017, 04:12 PM
#8
AudiWorld Senior Member
Clean all the pipes and filter, get brake shop to check for a dragging brake, buy the BEST gas, add injector cleaner occasionally.
hopefully you didn't WASH the wheels straight after driving, ........... warped disc ?
As said previous, check sensors.
Give her the occasional blow out on the highway ...
hopefully you didn't WASH the wheels straight after driving, ........... warped disc ?
As said previous, check sensors.
Give her the occasional blow out on the highway ...
Last edited by Pushbutton_auto; 09-20-2017 at 04:05 AM.
09-20-2017, 09:13 AM
#9
AudiWorld Member
I have 203k on mine and average speed driving around is 32 while average mileage is 21. On the highway at 70-80 I get 25+
I just realized that my post isn't very helpful. I think that the other suggestions are great, especially the brake grab issue. Jack the car up and try spinning each wheel. If you hear any noise or the wheel slows too quickly you have your culprit (or one of them)
I just realized that my post isn't very helpful. I think that the other suggestions are great, especially the brake grab issue. Jack the car up and try spinning each wheel. If you hear any noise or the wheel slows too quickly you have your culprit (or one of them)
Last edited by Dr. A8; 09-20-2017 at 09:23 AM.
09-27-2017, 04:05 AM
#10
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I had caliper guide pins dry up (no grease). This resulted in the brakes dragging on one of the rear discs. Its an easy fix, but I had to trash the rotor and pads (rotor was blue from overheating). Also, if your emergency brake is dragging (not adjusted properly), the motor is powerful enough to drive fine, but the car will slow down faster than you expect. As already suggested, jack the car up and test each wheel for drag.