Fuel consumption?

[dilateous]

According to the dashboard readout my 1.6 petrol Focus does 46 miles to the gallon.

On the other hand having logged all the fuel it's used and all the miles covered, my calculation comes out at only 37 miles to the gallon!!

And what's more, my previous car (10 year old 1.6 petrol) - which was a mere eight valve single cam job - did 36 miles to the gallon. But my current vehicle with 16 valves, double camshaft, variable valve timing and gismos my old car can only dream of, can only manage 1 extra mile!! And my new car has even got a £62 reduction in road tax on account of this extra efficiency!!

You are correct, I don't believe for one moment the 46 mpg dashboard readout.

[SonicHedgeHog]

I have a 1.6 petrol Fiesta. Probably the same engine. I get 45mpg virtually every time. 46.5mpg is the best for a full tank. Thats calculated at the pump. It's not what you drive, it's how you drive it.

[dilateous]

SonicHedgeHog said:

I have a 1.6 petrol Fiesta. Probably the same engine. I get 45mpg virtually every time. 46.5mpg is the best for a full tank. Thats calculated at the pump. It's not what you drive, it's how you drive it.

How the car is used or how one drives wasn't my query. But rather the clear difference between manual calculation and the built-in calculator displaying via dashboard readout.

For information the formula I'm using is:- Miles/(Litres x 0.264172) = MPG

[Zad]

dilateous said:

How the car is used or how one drives wasn't my query. But rather the clear difference between manual calculation and the built-in calculator displaying via dashboard readout.

For information the formula I'm using is:- Miles/(Litres x 0.264172) = MPG

There are 4.55 litres per gallon, you seem to be using 3.785 litres per gallon, which is the US gallon.

Your USA 46 MPG comes out at UK 38.27 MPG

ETA: They may be the same size, but how much more power does your new engine have?

[dilateous]

Zad said:

There are 4.55 litres per gallon, you seem to be using 3.785 litres per gallon, which is the US gallon.

Yes, that's where I am going wrong! Can't recall what I looked up for the conversion factor, but clearly got the yankee one! Thanks for that.

[dilateous]

And the MPG now comes out at 44. And my previous car comes out at 42 MPG. So more or less as before, the £62 reduction in tax is for the difference of just 2 MPG!!

[Rich's Granny]

you may be missing the point here....

cheaper tax is about how 'clean' an engine runs and how much emissions it produces not miles per gallon....

Got to add though that I don't necessarily agree with the taxation system but that's the idea of it.