40tdi fuel economy.


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May 21, 2017
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A6 40 tdi with 20" wheels car has done 1100 miles. Really not impressed with the MPG.

Today a steady run up the M1 at 70mph on cruise in Efficiency mode, and struggling to get above 40 MPG...

Is this due to it still being new and running in as I was expecting at least 50mpg.

Any ideas?

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That does seem low mate, perhaps the cooler weather had an impact?

In my 50tdi on 20's I'd comfortably expect 48mpg on a similar run.
Another thing maybe, if you haven't done a long run for a while, it might have been trying to do a dpf regen so running at higher revs than necessary?
Another thing maybe, if you haven't done a long run for a while, it might have been trying to do a dpf regen so running at higher revs than necessary?
I did wonder but it was the same in the week when I did a 200 mile trip. Gonn a keep my eye on it and may speak to the dealer, but would probably get more joy speaking to a brick wall,

I have noticed that when sat at 70mph on cruise control every few minutes there is an almost 'off the gas, on the gas' type hesitation. I assume this is something to do with the stop start system or the mild hybrid.

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Sorry I can’t help with your mpg figure...but just wanted to say you’ve tuned to a great radio station :thumbs up:
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You may want to try your next run in auto aswell and see what kind of mpg you get. I can honestly see no discernable difference in mpg between efficiency and auto mode in mine; and with the recent software upgrade the car is relearning my driving style and it does feel that it changes up quicker aswell now, so more economical in auto mode than it was initially.

Or I could be completely wrong and its just my perception degrading with age....
Check your tyre pressures, mine were really low when I picked it up, I had to put at least 5 psi in each. My 40 tdi has averaged just under 50 mpg in the 2 years I’ve had it.

But I agree with the previous post, the cold weather affects economy
Mine is averaging just over 50 mpg and is at just under 20k. It does improve over the first 10k.
The cold is affecting it at the moment and I have found that the mpg drops on wet surfaces and windy conditions.
I run mine in auto or individual-tried eco and it was annoying with no discernible difference.
Cold weather doesn't help: heating/heated seats/rear demister/heated mirrors will all affect economy.
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OP, I wouldn't worry too much - your engine still hasn't fully bedded in to give realistic MPG figures. I also have a 40 TDI Quattro with 20" wheels (black edition) and barely got 40 MPG when I had around 2000 miles on the clock, However after 12000 miles its now showing 46 MPG so fuel economy clearly improves as you clock up more miles, I believe the peak is reached at 20k miles. Btw I always use Drive Select in 'Auto', with standard 'D', and never drive like a boy racer. Fuel-wise, I always use Shell V Power Diesel, primarily to keep the injectors nice and clean.
I’ve done 800 miles in the past week, majority on the motorway, filled up today so worked out the economy to be just under 60 mpg. Got 730 miles out of this tank with an indicated 50 mile range left.

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