I've had exactly the same same kind of problems, however the readings given by the trip meter weren't eratic, I was getting the same by measuring fill up to fill up. I've just had all the updates, for the dash and ECU and instead of getting around 40MPG and a stumbly engine, I'm now getting 50+ MPG and smoooooth acceleration. After my initial disapointment the car now rocks. All I can say, is Ford, what are you thinking. Tell your dealers to get these cars in and sort them. How many Brits, will just put up with this, not complain, but just quietly never buy Ford again.