I have compared the dash with calculated on most of our cars and there is a difference.

Worst was a Golf, dash would say 48mpg, calculated would be 40mpg.

Current Leon says 49mpg, calculated is 45mpg.

Wifes kia Ceed is pretty much spot on.

But one thing to consider is the acccuracy of the cars odometer which makes a difference to the calculated figures. Checked against a Sat Nav another Golf we owned read approx 6% more miles than it actually covered. The Kia Ceed reads approx. 3% less than the distance covered. The trip to our lodge in Scotland is 430 according to the sat nav, the Ceed says its 416 miles wheras the Golf said it was 455 miles, a 39 mile difference.

Hi,

You spurred me on to trying this. I have an 2010 3L V6 petrol and so filled up with Shell Nitro+ (other premium petrol brands are available) and then did a ~420 mile round trip on the motorways & major A-roads of Engerland (i.e. I drove from W. Lancs to Cambridge & back via M61/M62/A1).

and then filled up afterwards.

trip computer recorded an av fuel consumption of 32.6mpg and I calculated 31.9mpg.

So more than accurate enough for me! And above what I budgeted for (30mpg on a run, 20mpg around town, I have managed to exceed this about 90% of the time in the past 2 & a bit years ownership).

cheers

Stu

have a sportbrake 200 and always employ the tank to tank technique rather than the trip. The official fuel figures are on average 20% removed from reality! Consumption has improved in the warmer months.

Recent tank to tank on long runs achieved 48.2 on the trip, never ever bettered that. in winter I have to accept about 39/40 actual.

Hope this helps, car is on Pirrelis 18" wheels, always kept clean and no weight.