Economy / Power Question

[Sp!ke]

Just use the measured CO2 figures. They are a direct indication of economy.

I'm not sure I agree on that entirely.

My wifes S60 D5 has quite a high banding (VED is £300+) because of its CO2 output and yet we regularly see 50mpg+. We got nearly 60mpg on a 1200 mile run.

Are we being cheated by the chancellor or is it an inexact science without direct correlation between CO2 and MPG?

 

[Dieselman]

The VED is calculated on what it achieved on the standard test cycle.

 

[Sp!ke]

The VED is calculated on what it achieved on the standard test cycle.

But surely the test cycle would give some indication of real world figures?

 

[Dieselman]

It's just a comparison, the same as published MPG figures.

 

[Bobby Dazzler]

The test cyclec don't really reflect reality - for example people seldomly accelerate in a truly linear fashion - it's simply to allow fair and consistent comparison between vehicles.

 

[Benzowner]

May I refer you back to Post #14.

The standard Co2 figures are calculated on the standard test cycle, which equates to a set mpg for that vehicle on that test cycle.

If the average mpg is known then the average Co2 can be calculated.

Take mactech's case of his Vectra at 71mpg.
(12.2/71) *620
=104 g/km.

pretty good and well below the published figure.

Maybe we need to set mactech a new target. 100g/km..

Sorry must have misses that, so are we at the mercy of the manufacturers and what they say the vehicle will do, or is this tested under laboratory conditions, or do they just take the mean of the fuel consumption figures i.e the "combined cycle"

 

[Bobby Dazzler]

See here for more on how official fuel consumption figures are derived:

http://www.vcacarfueldata.org.uk/information/fuel-consumption-testing-scheme.asp

 

[Mactech]

As we have seen there will never be a test which will represent what each of us will get in terms of mpg. There are simlply too many variables.

I was trying to point out from my own experience which was the best compromise have driven between power and economy (and I have driven quite a few!)
I will admit to trying to be economical in my driving, but I do like to have a great deal of 'grunt' available for safe overtaking.
I choose to own cars which are not basically that economical, but suit my need for comfort and power.
Doesn't mean that I can't get 50mpg from an S class and 40 from an ML though!