A4 Avant 2.5 TDi Quattro fuel economy

[Stuart7]

First post here, please be nice! :o

The car: A4 Avant 2.5 TDi 180 Quattro 5spd Auto Tiptronic, 03 Plate.

The problem: Average 29 MPG.

Ok, I know I shouldn't expect 50 MPG, but I've had the car 2 months, and I'm driving it very gently. I drive a mix of motorway and town, but with more motorway than town, maybe 65% motorway.

I thought I should expect closer to 35 MPG average, What Car online says 25.9 in town, 46.3 out of town, average 35.3. I reckon I'm 5 MPG lower on each of those, and my average on motorway alone was around 35, so possibly 11 MPG down on expected motorway consumption.

My numbers for average are calculated when filling the car up, so are accurate. DIS reports about 1 MPG better than my calculation. I'm not carrying heavy loads around.

The car is in great condition, full dealer service history, 97,000 miles, all fluid levels have been checked and are ok.

Is there something I should be aware of? Anything obvious I can check? Any advice?

[whiteakita]

you should be aware that alot of audi auto gearboxs are a time bomb waiting to cost £2000 to fix.
29mpg is really bad, my 1.9tdi was slightly sluggish and had bad mpg when i bought it because it had been owned by a lady driver for 3 years and hadnt been driven hard only town driving so i drove it hard for a week or so and the problem got better as the turbo de-coked itself.

[portugeeza]

I had a similar experience with my Allroad 2.5 tiptronic... my solution? Changed it for an A4 Avant tdi sport manual - averages over 40mpg mixed and up to 55 on a longer run. Much happier now and don't have the constant worry about whether the gearbox is gone give up!

[mark shutt]

i average about 35mpg from my 2.5tdi quattro sport avant, couldn't be any happier!! don't forget they're a big car and a 2.5v6 motor, considering this 29mpg is ok-ish and maybe it's because yours has high miles now and ready for some work on the engine? i dunno tbh :confused:

[spartacus 68]

i average about 35mpg from my 2.5tdi quattro sport avant, couldn't be any happier!! don't forget they're a big car and a 2.5v6 motor, considering this 29mpg is ok-ish and maybe it's because yours has high miles now and ready for some work on the engine? i dunno tbh :confused:

I wouldn't say high miles. The V6 unit should last the life of the car if properly maintained.

I'd be inclined to check obvious things first. Possibly fit K&N standard air filter, check EGR valve and turbo aren't blocked with carbon build up. Also Air Mass Filter may be faulty.

You can also run a can of Forte diesel conditioner straight into the fuel filter and drive the car hard. There should be a fair bit of black smoke initially until it clears. Replace fuel filter afterwards.

I have the smaller engine (AKN) 150bhp Quattro Avant - but regularly return 45mpg on A-class roads. Town driving is a different story.

[mark shutt]

i know the 2.5 should last a lifetime but it'll still get choked up just like any other engine and after 100k would probebly need a good service/decoke.

not sure if diesels actually suffer as much as petrols and what with todays cleaner fuel and more efficiant engines i'm not even 100% sure just airing my views.

[Pistunbroke]

Mine averages 35mpg on a good steady run (180 Quattro Sport Avant), which for the performance i think is pretty good. Yours is auto box which will slightly lower your mpg due to torque converter action.

[sr-performance]

as spartacus says put some forte through engine, it's very good stuff.. then have it remapped but i'm biased.. :beerchug:

[Stuart7]

Interesting responses, I'll maybe try some forte through it...

sr-performance, I've been wondering about re-mapping, but not sure how that helps with an auto 'box? Surely the auto box "program" remains unchanged, so the box doesn't know the engine's response has changed, so there's no benefit? Or am I missing something? I can see that with a manual car, you can easily change your gear change habits, but the auto is fixed...

[sr-performance]

Hiya mate,
when you remap, it physically alters your torque settings etc so you can make the engine respond better at low revs, so as it is now stronger at lower rpm you dont need to rev the engine as much due to the increased torque settings.. hope that sort of explains it a bit.. :beerchug:

[Stuart7]

Hiya mate,
when you remap, it physically alters your torque settings etc so you can make the engine respond better at low revs, so as it is now stronger at lower rpm you dont need to rev the engine as much due to the increased torque settings.. hope that sort of explains it a bit.. :beerchug:

Ok, and I see how that helps when you have a manual gearbox, you can stay in a higher gear where you might have shifted down...

If I have an automatic, the car decides when to change up, so I would get increased performance, but no improvement in fuel economy. Unless there's a way to tell the gearbox it can change up at lower revs than before...

[sr-performance]

Hi mate,
You will get better fuel economy as everything in your engine's ecu is optimised and as there is more torque lower down it changes your engines characteristics.. :beerchug:

[spartacus 68]

i know the 2.5 should last a lifetime but it'll still get choked up just like any other engine and after 100k would probebly need a good service/decoke.

not sure if diesels actually suffer as much as petrols and what with todays cleaner fuel and more efficiant engines i'm not even 100% sure just airing my views.

Not a criticism. Yes the engine can get carbon build up, especially around the breather hoses, EGR valve, turbo, exhaust manifold, etc.

[sr-performance]

No prob mate,
I always put a bottle of forte in tank once a month, seems to work a treat as I have never had any probs with any egr or carbon probs since using it on various cars. :beerchug:

[skdotcom]

I too have a 2.5tdi tipronic and think 29 mpg doesnt sound that bad.

I find mpg is bad around town and on short journeys, and would expect sub 30mpg if driving in these situations I tend to flip it to manual mode and change up the gears up sooner to try and improve the economy.

I average 32mpg, but on a run can get 40mpg ish.