Poor MPG. Advice needed

[RMJonny]

Awlrite folks!

I recently got an A6 Avant Sline 2.0 170 and im struggling to get over 40 mpg. it can be anywhere from 29-39 is this normal? I am doing a mixture of trips but even on long runs cant get it above 40

Cheers

 

[elan2s]

You don't say if this is a C6 or the new C7 platform but would agree these do seem a bit on the low side. However if it is a new car then it should improve over the first 5k miles or so as the engine loosens up. Another factor is the time of the year. As it is winter the car is not only having to run in cold start mode more frequently but also as it is a diesel it will be running the auxiliary heater to get the heater up to temperature (diesels are thermally efficient and so it takes longer for the water in the engine to heat up and thus the heater needs a boost when cold). Finally it will depend on the types of journeys you are doing, although if it is a new C7 A6 you should have stop-start which should help.

 

[RMJonny]

Hi, yeah sorry its a 60 plate with 4000 miles on the clock, not sure what that makes it. Didnt know it has a seperate heater to the main one. It doesnt have the start stop feature your talking about.

 

[elan2s]

OK, sounds as if it is a C6 platform. Depending on your driving style I would expect you to be getting better consumption than you are, however the engine is still fairly new and probably a bit tight. I have the same car but with the 136bhp engine and get over 40mpg average all the time and on long motorway runs cruising a 80ish I have seen high 40 and even low 50s. Suggest you give it a bit longer and if the mpg is not getting better have a chat with the dealer. Also check the tyre pressures, especially if you have not done it recently, the cold air temp can cause them to drop 2-3psi on its own ignoring any incorrect inflation and this can affect your fuel consumption

The auxillary heater can be switched off via the MMI system, but if you do it will take longer for the interior to warm up

 

[RMJonny]

yeah, will give it another couple of k but think i will get a tuning box for it see if it helps any. tyres are all spot on but i have turned off the aux heater, see if that makes much of a difference. regretting not getting the 136bhp now

 

[elan2s]

Had another thought. With car being about 1 year old and only 4000 miles on the clock it has either sat around alot or it has done a lot of short journeys. If it is the latter then it is very likely that the DPF is clogged. The car clears this itself by passing unburnt fuel into the filter and allowing it to burn in there and thus clear out the material that has been collected. This clearly will have an effect on the fuel consumption whilst it is doing it stuff and requires a good high speed 50 mile drive to really clear out the filter. If it does not fully clear each time then it starts the whole cycle over again the next time you start the car.

 

[RMJonny]

Good point, i will get out for a good run this weekend. I think i just need to suck it up and accept it is going to be quite thirsty as its a heavy big car. Really appreciate your feedback though. Its good to have someones advice when your not clued up on these things so cheers buddy!

 

[quikstu]

Hi, can I resurrect this thread?

Last Friday I purchased a secondhand A6 Avant S-Line 2.0TDie 136bhp "09 plate" with 73k on the clock. It is an ex company car so i would presume has done mostly motorway miles.
Anyway, my issue too is with the fuel consumption. The readout states I am only getting 35mpg on average when I was expecting 45ish.
I do not know what the SPF is but the theory of it being clogged makes sense. Should this high speed 50mile drive de-clog it and improve consumption?

Thanks.

 

[elan2s]

Which gearbox? My previous A6 was a manual '09 2.0 TDie SE Avant and I never got below 42mpg as a 2 tank average (c1000 miles). My driving tends to be mainly shortish journeys on open country roads. If you have an auto (CVT gearbox) and/or do a lot of town driving then I would expect the consumption to be lower.

The DPF (Diesel Particulate Filter) is designed to trap the nasties that are left after diesel fuel has combusted. Periodically the filter needs to empty itself and this process requires the burning of additional diesel, hence the impact on consumption. You can often tell this is happening as their is strange smell when you get out of the car. If the process does not happen properly you will get a warning light on the dash and need to drive the car in a lower gear (ie higher revs) for a period as described in the handbook to clear it. A good high speed drive, as you suggest, should certainly get it to go through the clearing process if it is required. Also check the tire pressures. Dealers have a habit of ignoring or incorrectly setting them.

 

[Audi Dynamik]

Switch Your Air con off, Try Shell V Power, Ive tested it and it actually gave me more Mpg, but the Fuel is more expensive but it pays for it self the amount more Fuel it Gives, it also increases performance and is better for your engine, as it is quite low mileage very soon when you clock up a few more you will start to see a bit of a difference, also it depends on your driving style, Say if you drive like a maniac you are bound to use more fuel !

 

[Aly]

Mines is a 2.7tdi and I'm lucky to see 25mpg in town! And that's driving like Miss Daisy!

 

[ChrisFurlong]

I'm lucky to see 18 around town! And 30 on a long journey!

 

[hazey7]

These 170bhp TDI engines used to give 50+ mpg before the DPF was fitted as standard, there is quite a lot of posts and history on these engines, the DPF factor and claimed/actual mpgs throughout Audi websites.