B5.5 TDI Very Very Low Mpg :o(

[Dimka]

Hi there. This is my first post on this forum and I'm hoping some of you guys might be able to help.

I have a Passat TDI 130 1.9 Manual with 75k on the clock. Bought this car in November. So I've been driving for almost 3 months and have never archived the magic number of 50 mpg.
The car is incredibly thirsty! The average mpg is JUST 36-38!!!
The best I could get out of it was 40 while free-wheeling at the first opportunity.
My round trip to work in about 40 miles a day, carriageways, no traffic, no traffic lights, just free run with the average speed of 50 mph. (My old Toledo 110 TDi with 190k on the clock returns about 52 mpg on that route)
There appear to be no other symptoms and the car does seem to run well with plenty of power, and there's little or no smoke from the exhaust.

Took the car to the garage 2 weeks ago. VAG-COM test showed a faulty engine temperature sensor.
So got a new one fitted along with the new MAF sensor. The also took all the injectors out and cleaned them. Cleaned and tested EGR sensor. Total bill over £300.
Effect on fuel consumption – ZERO!

Took it to another garage. They only pointed out that gearbox mounts on their way out and need changing soon. I personally don't think that it would improve the mpg.

I'm really frustrated and don't know what to do. I keep spending money on that car with no result.
I thing something is fundamentally is wrong with that car. One of my mates pointed out that the timing might be out (The belt has been changed by VW guys at 65k)

Anyone any ideas?

Regards