1999 A6 2.5 TDI Quattro economy - how to improve?

[sublimatica]

Hi all. Wonder if anybody can help...

Just bought a second-hand 1999 A6 2.5 TDI Quattro Avant auto/tiptronic through Pistonheads (Hi Nick, if you're reading this ) and I'm disappointed with the economy I'm getting. The first full tank of fuel gave me only just 400 miles, at 29mpg. I'm driving normally and with the same driving style I used to get 30mpg+ out of my 2-litre petrol E-Class.

Is there anything I could check/change to improve the economy? Does the MAF sensor affect economy? Do injectors wear out and over-fuel? Anything else worth checking? The car's done 104k miles.

The performance of the car is good, with no excess smoke. I know the Quattros aren't as good as the FWD cars, but are they *this* bad?

[ukross]

Depends on your driving style, but it's a big heavy car and I would say that as a mix of town and mway driving, that looks about right - if its on the low side its only by a couple of MPG which can easily be accounted for by individual driving styles.

Unfortunatly, the combo of quattro/auto often the negates the advantage of filling up at the black pump when compared with a manual/2WD.

Have you taken it on a long run yet? A 400 miles round trip on the mway at 29mpg would certainly look a bit low.

[deva link]

I think that with diesel auto's is takes a lot of effort to get them moving, and I would imagine that a 4WD drive one would be worse than 2WD, so I make a huge effort to avoid stopping, and use a lot of anticipation in town driving.
The other thing with diesel's is it takes a long time to warm them up. Yours might have electric engine heat assist which will whack the economy in cold weather.

I drive a Merc C270CDi Estate and it only does about 30MPG around town (5-10 mile journeys), but will do 40MPG on 'mixed' driving, and I can get 50MPG on the trip meter if it's a long (175 mile) steady motorway journey. I notice on long journeys that the fuel consumption doesn't settle down (or up!) until I've done about 40 miles.

[POORCARDEALER]

I had the ALLROAD model sold it after 2 weeks, was also Tiptronic, was doing average 25mpg and yes it was a TDi!!!

[Yertis]

I tried the tiptronic AllRoad Tdi and it was awful, could feel the economy was going to be shite because the car felt so leaden. Now have a manual AllRoad Tdi and whilst I'd not go so far as to call it frugal it's not awful. 29mpg around town, 32mpg on the motorway. May not be great mileage for a diesel but compared to what I'm used to in the S4 and TR6 it's positively frugal. Moves along quite nicely too if you work at it.

[sublimatica]

Well, an update here after the doom and gloom this morning...

Drove from Sussex up to Bluewater in Kent this afternoon - 100 mile round trip on mainly motorway. I reset the MPG average as we left, and when we arrived at BW the average was nearly 38mpg. Coming home the average shows 36mpg.

The cause? I fixed the gauge on my tyre foot pump and checked the pressures before we left - all tyres were at 28psi instead of the recommended 36. I pumped them all up to 38 and left the AC off. Set the cruise at 80mph but didn't drive especially carefully otherwise, and there was plenty of 50mph-80mph variation during the journey.

It's amazing that the tyre pressure and AC could have such a dramatic effect - a similar 100 mile round trip to Heathrow yesterday certainly didn't give me decent economy.

So I'm a whole lot happier now. The seller suggested 36-40mpg on a run and this seems entirely achievable. I'll find out in January when we drive down the Péages to go skiing. 30mpg would have been devastating.

Thanks to all who replied above.