Trip Computer - Is It Working Properly?

Hello everyone,

Just joined this forum after having bought (from a main dealer)a 2.0 TitaniumX auto diesel 57 plate 40,000 miles.

Had it a week now and a few little niggles to go back to the dealer about but the main one is the way the trip computer is working, or not!

Previous cars I have had with a trip computer have always worked how you would expect and the 'average' mpg starts being computed straight away after being re-set and settles to a sensible figure within a couple of miles. For example on my last car, from garage to home (6 miles) it read 42mpg and this settled down after a few runs to a fairly constant 37. (For clarity I am talking about the computed 'average' figures not the instantaneous one that some systems supply in addition.

I picked up the Mondeo, filled the tank, and zeroed the trip and average mpg counters. I drove 10 miles (straight road, little traffic, 50 speed limit)and saw that the average mpg was shown as 7.2, the average speed was also stupidly low. Anyway I left it set to show mpg so I could keep an eye on what was happening and over the next few days the mpg gradually crept up and up until after about 50 miles it is showing 22.1 mpg. Is this a normal way for these systems to act? do they take many miles to record an accurate mpg and should not therefore be re-set often? If so, it is a bonkers system, and I can't think that it is right.

Trying to search for any info on it I did see many tales about the DPF filter (which I think my car has - don't know how to tell for sure) so now I am thinking that either the trip computer is buggered in some way, OR the mpg figures shown are possibly correct and the DPF has not been regenerating as it should. Of the two I hope it is the first!

I intend to take the car back next week but would like to go armed with a bit of knowledge so I don't get fobbed off, so if anyone can help with this I would be grateful.

Apart from that it seems on short acquaintance to be a very nice car, nice looking, stacks of room and drives like it wants a driver behind the wheel.

Thanks for any help that might be comimg

Peter