The Sharon is a big vehicle. The numbers aren't spectacular, but not way out.

Thanks, you made a good point. The Passat is as light as a feather in comparison to the Sharan!

Remaps/chips do not improve mpg. To put it simply a diesel car requires a certain amount of power to maintain a certain speed, the fuel to produce that power does not change even with a re-map, no clever bloke and a laptop can change that. Read the adds carefully, they all contain weasel words that mean you can never take them to court, they never promise, they simply suggest you may get better mpg.

Drive slower, you WILL get better mpg.

Also consider that even if a wonder chip did improve your mpg by 5% how many miles would you need to do to recoup your £400 outlay. Quick tap at the calculator for your Sharan suggests about 55,000 miles. Not an instant solution is it.

Thanks to you and others for helpful comments. The analysis above of differences in winter to summer is very interesting.

Nutkey, I am delighted that you are getting v similar MPG to me, because it indicates that despite mine having done 132k there is no specific hardware or software fault causing this. But it would be good if MPG was better for both of us! I tend to stick to speed limits (my 5 year old has learnt to read the speedometer).

The thing that puzzles me is that I am getting near to the mfr claimed MPG on my Passat but I (or should that be we?) are not on the Sharan/Alhambra, but with the same driving style.

It occurred to me that one difference is that the 2011-> Sharan/Alhambra has an auxillary heater. I knew nothing about this until my mechanic demonstrated that there is an extra, little (2cm diameter) exhaust approximately below the position of the driver's side front foglight and this little motor starts up at temperatures below 10 degrees centigrade to provide additional heat to the cabin to warm / demist it faster.

I got 24mpg this morning on a 4 mile school trip (I know, I know, we should have walked) and we all had coats on. I would have prefered the better economy to a little bit more heat, if I could de-activate the Aux heater.

1: Does anyone know if it is possible to take the fuse for the Aux heater out to see whether it improves MPG? (If it does, I might consider fitting a bespoke under-dash switch to only activate the Aux heater when I want to)...or have I got the wrong end of the stick?

2: Can anyone explain more about this mysterious little motor? Does it run from diesel or is it electric? Does it de-activate once the car enginer has warmed up, or only once the ambient outside temperature is above 10 degrees?

Thanks again for all replies. Anted

6) Allegedly, the rules allow manufacturers to overinflate tyres, run the test at altitude (less air resistance), and seal up all the gaps. For all I know it's legal to fold the mirrors in too.

That is a load of rubbish;get yourself a copy of the regulations!