WE MADE THE DREADFUL MISTAKE BACK IN AUGUST LAST YEAR OF PURCHASING THE FIAT500 TWIN AIR, AND FROM DAY 1 IT FAILED TO DELIVER ON THE ADVERTISED MPG.

I COMPARED THE FIGURES WITH SEVERAL CARS WE HAD OWNED AND WITH OUR OTHER CURRENT CAR - SEE BELOW

Fiat Grande Punto 1.4 petrol (advertised mpg 47.9) (Actual 45) (achieving 93.9%) (loss 6.1%)

Honda crv2.2 diesel (advertised mpg 43.5) (Actual 40.4) (achieving 92.8%) (loss 7.1%)

Peugeot 308 cc 2.0 diesel (advertised mpg 47.8) (Actual 44.7) (achieving 93.5%) (loss 6.5%)

Suzuki swift sz2 1.2 petrol (advertised mpg 56.5) (Actual 47) (achieving 83.0%) (loss 17.0%)

Fiat 500 TwinAir950cc petrol (advertised mpg 68.9) (Actual 47) (achieving 68.2%) (loss 31.8%) 

THE MAIN REASON FOR BUYING THE CAR WAS FOR THE GOOD MPG, DESPITE COMPLAINING TO THE DEALERSHIP, FIAT CUSTOMER SERVICES AND TO THE FINANCE COMPANY (FIATS OWN) THEY HAVE COMPLETELY IGNORED OUR COMPLAINT ONLY SAYING THAT THE FIGURES THAT ARE USED ARE BY AN INDEPENDENT COMPANY AND THAT WE MUST NOT BE DRIVING IT PROPERLY. WELL IN SEEMS STRANGE THAT ALL THE OTHER CARS WE HAVE DRIVEN HAVE BEEN ABLE TO DELIVER OVER 90% OF THEIR ADVERTISED FIGURE YET THE FIAT 500 TWIN AIR FAILS DISMALLY TO GET ANYWHERE NEAR. 

WE HAVE BEEN TRY AND TRYING AND COMPLAINING TO VARIOUS TRADING BODIES ABOUT THE SALES OF GOODS ACT AND THE MIS-REPRESENTATION ACT BUT IT SEEMS THAT THESE RULES ONLY APPLY IF YOU BUY A KETTLE OR OTHER FAULTY GOOD BUT NOT TO CARS THAT DON'T DELIVER WHAT THEY ADVERTISE.

IF FIAT REALLY DO CARE ABOUT THEIR CUSTOMERS THEY WOULD ADMIT THAT THEY GOT THE FIGURES WILDLY INCORRECT AND THAT IN THE REAL WORLD THESE FIGURES ARE NOT REALISTICALLY ACHIEVABLE AND THEN CONTACT THEIR CUSTOMERS AND APOLOGIES FOR THE MIS SELLING THE CARS TO US SO THAT WE CAN RETURN THEM AS WE WOULD A FAULTY KETTLE. 

FIAT; IF YOU REALLY DO CARE ABOUT US THEN DO SOMETHING ABOUT IT.

 Case numbers 32249070 & 32522002. Contact us like you said you would and sort them out.

Much the same here.
Since new my average is 37mpg and that's with the auto gear box (another source of dispair)
I've complained to dealer and Fiat, Officially asked for the car to be returned and refunded twice.
First time re: MPG, it's your driving style!! and it will improve with, first 5000 then 12000 miles use. I'm at 8000 miles and it's still NO different ie. 34-39mpg as it was when new.
Second time re: Dualogic gearbox, trying to drive in eco mode while 'auto' holds on to 5th gear at 1100rpm. Advised by dealer to not use eco mode!
  Give it a go with manual box and you'll see want I mean.

Anyway both time they refused to take the car back saying everything was as spec and the diagnostic tester found 'NO FAULTS'

I do enjoy driving the car apart from the above two 'FAULTS', sorry 'NO FAULTS'
I'd be happy if Fiat accepted and 'FIXED' the 'No FAULTS', I'd then buy another new Fiat later but not after this.

There MUST be something that can be done?????

I spent over £15000 for a promising economical 2 door 2 cylinder 875cc small car to achieve 37mpg!?$%?

We feel extremely angry and let down by Fiat, feel like driving it through the dealership window some days or parking it outside with a big sign on the side of the car saying 'do not by a Fiat because they are crap'. 

It seems like that might be the only way to get Fiat or the Dealership to take us seriously. Like you say for a car with 'no faults' it sure has a major one when it comes to the mpg figures.