Mpg worse after a service

[Gareth Johnson]

Just had the car serviced after 19k and now the mpg has dropped by around 10 to 15% based on the computer. Anybody else had anything similar?


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[Guest 2]

Same journeys? Remember cold weather will have a negative affect on mpg too.

Do a brim to empty and see if there's any difference from before.

[zollaf]

are you looking at instantaneous or average. a service will always involve a spirited test drive to check for vibrations, clutch slip and make sure the brakes are working as they should. this can knock the average mpg down no end but is actually a vital part of checking a car is safe.

[johnsimcox]

also if it is the long term average, then remember the car will have been sitting in the garage stationary with the engine running for a period of time during the service as well. It may be that the service process (sitting stationary etc) has triggered the DPF to regenerate burning more fuel

[Gareth Johnson]

Hi. My reading we're taken over a 40 mile run each way. Mainly motorway driving with a little bit of town driving each end. I would normally expect the short range consumption monitor (which I reset) to be around 44-45. It did 38 one way and 41 the other in reality which is the worst I've ever seen it.


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[Guest 2]

Outside temperatures? Load, luggage, people etc? Could be doing a passive dpf regen.

[Wuffles]

Hi. My reading we're taken over a 40 mile run each way. Mainly motorway driving with a little bit of town driving each end. I would normally expect the short range consumption monitor (which I reset) to be around 44-45. It did 38 one way and 41 the other in reality which is the worst I've ever seen it.


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That's multitronic territory. Unless that's what you are in?

[Gareth Johnson]

Hi. It is a multitronic but I've had reasonable consumption of around 46mpg on the motorway before the service. Very disappointing. Will be calling audi tomorrow to be fobbed off for a guess.


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[Wuffles]

What you are getting now is what I've always had in this kind of weather (up to and incuding 25k), apart from in the super sunny weather when we got more like the figures you were getting before your service.

At least you know you'll be fobbed.

[Passatier3]

Bit frustrating to note this before and after a service but I'm with Wuffles that in the summer I was getting mid to high 40's and am now getting 38/39 and maybe 42 if taking it easy.

I'm probably driving it slightly harder but think it's more down to the engine taking longer to warm up (the main culprit) and aided and abetted by use of the heater, wipers, lights in rain and dark etc. which all add up.

[Steve Hut]

I have noticed a drop off as well with regards to mpg and being noticable lower now with colder weather. Could get mid to high 40's if really gentle and now getting low to mid 40's. Mine its 36k service in a couple of weeks as just passed 32k.

[Gareth Johnson]

Thanks everyone. General consensus is poorer weather is the offender with the car need more time to warm up. I have a trip on the m4 planned this weekend so I will brim the tank and see how it goes.


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[ti rich]

i think it's the auxiliary heater kicking in. It appears to activate below about 10C in my opinion and as soon as it does the MPG drops significantly. I switch it off and wear a coat!!!

[Gareth Johnson]

Did a controlled test yesterday, well as controlled as I could get in the real world. 148 mile round trip on the m4, cruise control set at 75 mph and I got 40mpg going and 44mpg coming back. Temp was around 11 to 13 degrees but I had turned off the supplementary heater to stop it from being a variable. Would have liked better but will monitor it for now.


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[Passatier3]

Some reckon that using the cruise control makes the fuel consumption a little worse. Thinking being that it keeps accelerating to maintain speed up inclines whereas we'd maybe allow the speed to drop a bit and then gently accelerate back up to cruising speed.

[Olio]

True about adaptation, but when I put the CC on, the engine rpm drops noticeably (say from 1700/1800 rpm to 1100, with no change of speed)

I'll try and get a video if I can.