Poor mpg

[glen1992]

Hope someone can help me.

I bought this Audi a4 b8 2008 2.0tdi 170bhp but getting shocking mpg around 29 mpg driving locally and 34 mpg on motorway run. Got it terra cleaned and full service all the filters changed and still getting the poor mpg. I had diagnostic check nothing came up. Now I am thinking to sell it… lovely car but can’t be keeping a car like this specially if I do a lot of miles per year. So can anyone tell me if the mpg is correct or there is something wrong with my car? Thanks

 

[spartacus 68]

I run an A4 Allroad, so the best I’ve had on long drives at 60mph is around 40mpg in efficiency mode if you have drive select fitted. I can probably coast into a petrol station on fumes and expect 500 miles out of a full tank.

It’s a heavy vehicle, not sure if this is a Quattro too? If it is, then that knocks off a few mpg. Remove storage roof boxes or Thule bike carriers if fitted, and run tyres at correct pressure should all help. I run Mitchelin Cross Climate on mine. Low road noise and I think it’s quite a hard rubber compound.

If you’ve had a terra clean, I’ve not so can’t comment, then you should expect something? On my last Audi (B5 2.5 TDI V6 Quattro Sport Avant) was probably worse for fuel. I cleaned out air intake manifolds at 150k miles as there was carbon build up. I’ve also just put a new turbo on the Allroad. I think it failed prematurely at 65k miles, but on inspection of the old one there was carbon there too restricting the actuator movement. Again that all has an effect on efficiency. If you pull the turbo to inspect, then you’ll need to do an oil change and you’ll need gasket fitting kit.

You can get injectors checked for flow control and cleaned. Depends on mileage. I’ve also read getting the ECU mapped on the 170PS improves fuel efficiency as well as improving torque.

I also used to run Forte diesel conditioner, again this was to get my B5 Amtrak locomotive through an MOT, especially if it’s a little smokey on start-up. You need to change the fuel filter afterwards. Pulled like a train though.

Have you run VCDS on it to see what it’s doing?

 

[Simon]

what are the book MPG figures for it, and how do you drive it?

MY GTR will do 35mpg if I drive like a granny on the motorway. Most of the time it does around 22.

 

[Gazwould]

https://www.honestjohn.co.uk/realmpg/audi/a4-2008

Thermostat is a good place to start.

 

[glen1992]

Not Quattro just 2.0 tdi s line. Got around 167k mileage however new engine was fitted a few years ago that only had 80k. I drive to speed limit and occasionally put my foot down when needed. Went from Newcastle to Manchester and back on full tank only got 420 miles that calculates around 35mpg. This car got 6 gears also. So was expecting to get over 40mpg. If it was the thermostat would it came up when it was on diagnostic? Not checked VCDS what it is doing. Seeing if anyone got same model and what they getting on full tank? I have put redex many times and nothing really improved

 

[spartacus 68]

Good call Gaz. I know nowt about the cooling system and thermostats on the B8. Dave Sterl has a video on his YouTube site Specifically about TDI system.