Poor fuel mileage on my 2000 A8 Quattro
10-19-2017, 01:04 PM
#12
AudiWorld Member
I just turned over 250,000 miles on my 2000 A8. I get an average of 22 mpg and I drive 135 miles per day, twice a week with a 80/20% mix of interstate/city driving.. I can tell you that the best fuel mileage I have ever had was 24.3 mpg and that was on a cross-country trip all highway. I have owned this car since 114k miles.
I only use OEM spec Bosch 4 ground electrode plugs, and I change them at 40k miles (factory interval). I change my fuel filter every 30k miles. Transmission fluid every 30k miles.
From my experience, bad fuel economy is normally attributed to worn out spark plugs, clogged fuel filters, not changing out the "lifetime transmission fluid," VACUUM LEAKS from any of the myriad of hoses routed through the engine compartment, a HOLE (that I patched) in the secondary air injection hose that is routed from under the air filter box and around the back passenger side of the motor. ALL my O2 sensors were replaced around 130k miles. Here's another simple one: the main air intake tube may not be completely sealed. When I originally bought my car, the former owner had somehow folded one of the connection boots under the screw clamp which leaked air into the intake, downstream from the MAF sensor. This assumes that your alignment is dead on accurate.
Hopefully this gives you some ideas to try.
I only use OEM spec Bosch 4 ground electrode plugs, and I change them at 40k miles (factory interval). I change my fuel filter every 30k miles. Transmission fluid every 30k miles.
From my experience, bad fuel economy is normally attributed to worn out spark plugs, clogged fuel filters, not changing out the "lifetime transmission fluid," VACUUM LEAKS from any of the myriad of hoses routed through the engine compartment, a HOLE (that I patched) in the secondary air injection hose that is routed from under the air filter box and around the back passenger side of the motor. ALL my O2 sensors were replaced around 130k miles. Here's another simple one: the main air intake tube may not be completely sealed. When I originally bought my car, the former owner had somehow folded one of the connection boots under the screw clamp which leaked air into the intake, downstream from the MAF sensor. This assumes that your alignment is dead on accurate.
Hopefully this gives you some ideas to try.
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