2005 A4 getting bad fuel mileage
3rd Gear
Joined: May 2009
Posts: 1,682
From: South Korea
That could be one, but I doubt is going to help greatly on the fuel economy. I just talked to a guy with an A6 and a B5 S4, they also saw a decrease in their fuel consumption, the B5 didn't really do that bad but me and the A6 (we both have 3.0) went down to half of the whole consumption, meaning we're getting about 220 MPT, compared to 380 ~ I used to get in California.
1st Gear
Joined: Nov 2010
Posts: 2
MossyOak,
I came to this forum for almost the identical reason. Although I have a 2004 A4 1.8T, I would fill up after getting 400 miles per tank and for my trip to and from work I would average approx 30 MPG per the computer calculation. Other trips were obviously less, on average.
I recently had my 75K mile maintenance including new timing belt, and got new tires the follow week. I then noticed the computer registering about 5-7MPG less for the same trips i've always taken. Even after driving for 10 mins if I went up a hill or had to accelerate from a red light it might go from 22 to 18 (average)... I never noticed such swings in the MPG average. I put it on instantaneous reading and on a flat road going 30mph it was steady at 19. weird.
I replaced the michelins with the same size tire size (Continental Contiprocontact 215/55/R16 93H). The tires I replaced were down to about 2/32" tread in the back and maybe 7/32" in the front. I believe before i bought CPO that the dealership put on two new tires only.
Other side note, I recently had the secondary air pump replaced.
So after I noticed this change in average MPG I did some online research and heard about brake drag. This is where the brake is touching the pad even when the brake pedal is not touched. I called the tire place and they said unless I smelled something and had the car pulling to one side that that was unlikely. I brought it to the Audi dealership for a new headlight and asked that they look into this. They did the diagnostics and said they found nothing.
Here are some possible reasons:
1. My tire is larger than before since it has new tread. So it rotates fewer times for the same distance meaning that the computer was over estimating before, or underestimating now. Either way, it is registering less mileage. I may be burning the same gas for the same actual mileage as before.
2. it is slightly colder now, but even on a 60f day there was a noticeable difference.
3. I have always used the cheapest gas. Most recently i used the highest octane to see if it would make a difference. Assuming it would have an immediate impact, this did not change anything.
4. perhaps the new tires are somehow causing less rolling or more drag. (?)
5. Something happened during the 75K maintenance. Timing belt changed something?
6. The computer is malfunctioning. Not sure how it works but maybe dirt is on a sensor. I find this hard to believe.
7. what else could it be?
I came to this forum for almost the identical reason. Although I have a 2004 A4 1.8T, I would fill up after getting 400 miles per tank and for my trip to and from work I would average approx 30 MPG per the computer calculation. Other trips were obviously less, on average.
I recently had my 75K mile maintenance including new timing belt, and got new tires the follow week. I then noticed the computer registering about 5-7MPG less for the same trips i've always taken. Even after driving for 10 mins if I went up a hill or had to accelerate from a red light it might go from 22 to 18 (average)... I never noticed such swings in the MPG average. I put it on instantaneous reading and on a flat road going 30mph it was steady at 19. weird.
I replaced the michelins with the same size tire size (Continental Contiprocontact 215/55/R16 93H). The tires I replaced were down to about 2/32" tread in the back and maybe 7/32" in the front. I believe before i bought CPO that the dealership put on two new tires only.
Other side note, I recently had the secondary air pump replaced.
So after I noticed this change in average MPG I did some online research and heard about brake drag. This is where the brake is touching the pad even when the brake pedal is not touched. I called the tire place and they said unless I smelled something and had the car pulling to one side that that was unlikely. I brought it to the Audi dealership for a new headlight and asked that they look into this. They did the diagnostics and said they found nothing.
Here are some possible reasons:
1. My tire is larger than before since it has new tread. So it rotates fewer times for the same distance meaning that the computer was over estimating before, or underestimating now. Either way, it is registering less mileage. I may be burning the same gas for the same actual mileage as before.
2. it is slightly colder now, but even on a 60f day there was a noticeable difference.
3. I have always used the cheapest gas. Most recently i used the highest octane to see if it would make a difference. Assuming it would have an immediate impact, this did not change anything.
4. perhaps the new tires are somehow causing less rolling or more drag. (?)
5. Something happened during the 75K maintenance. Timing belt changed something?
6. The computer is malfunctioning. Not sure how it works but maybe dirt is on a sensor. I find this hard to believe.
7. what else could it be?
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