I got my Punto Sporting MK2 MOTed yesterday, 3rd MOT but car only has 10,300 miles on the clock as I work form home and don't drive it much.

At the same time I asked that they change the oil and oil filter - they provided the filter and I had already bought Chevron Fully Synthethic Oil which has pretty high specs.

I only got to drive the car a short diatnce so maybe not enough time to see - The car does some to be a bit smoother and faster now, BUT the MPG reading on the car is saying about 24 to 25 MPG when usually it's about 34 MPG about town (no traffic)

Could an oil / filter change have affected the MPG to do down but this much?

Only other thing I can think is the tyre pressure is lower due to something that happened during the MOT or just that this is a computer glitch?

I'm to to try and take the car ona longer runtoday and maybe stop by a petrol station and check the tyre pressures - but any ideas in the mean time?

Have you reset the trip computer? During the MOT they run your car reving it checking the emissions. This will cause the MPG to go down considerably. The computer takes an average reading from when it was last reset and therefore it will take into account the beating that the MOT guys gave it.

Dave

david.willis said:

Have you reset the trip computer? During the MOT they run your car reving it checking the emissions. This will cause the MPG to go down considerably. The computer takes an average reading from when it was last reset and therefore it will take into account the beating that the MOT guys gave it.

Dave

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I zeroed the counter - nice day today so will go on a long drive (long for me anyway ... lol) and double check it

Well it took about 10 miles of driving but the MPG's seemed to have settled down and now reading inthe mid 30's MPG - probabaly actually getting 1 or 2 MPG's more then I did before.

My local fiat garage reset my ECU last year (when I got it) as it was revving eratically, and for a few weeks after that the MPG's were down and had lost a bit of power, the only thing i can think of is it was running too rich after being reset.
You should reset trip to get a new reading. make sure its warmed up when you are reading MPG's as cold engine will run rich.