As a prospective owner, I am going through the specs for the different trim levels. Can anyone tell me why the '3' and 'First Edition' have much higher official emissions (+15%) and much lower official mpg figures (-14% combined) ? At first I put this down to wheel size, but the circumference of the tyres (205/60R16 and 225/45R18) is near enough the same. Is it the extra weight/inertia of the bigger wheels, or extra loads on the battery (and the engine, to support charging) or is it something else ?
18" wheels might be slightly heavier but I think the main effect is higher rolling resistance owing to the greater width of the tyre. 225mm wide = nearly 10% wider than the 205mm 16" boot, so more rubber to stick to the road. Good for going around corners maybe, but not helpful for economy.
If it's any consolation, I puzzled over the issue and went for a "2" spec with ADAP, but if I could have had the "3" on 16" wheels I probably would have done. Will miss the heated seats in my current car
Thanks. I didn't think about the extra tyre width. That makes sense.
I am considering getting a '2', but I have timed it badly with the changes to vehicle tax on cars registered from the end of this week. If I want to take advantage of the old emissions-based taxation I may have a limited choice of ex-demo and pre-reg cars. If I buy a '3' then I wanted to understand why it uses more fuel, although I don't see myself buying a '3' plus a set of 16" wheels - it would take several years' worth of fuel savings to recoup the cost !
I think it'd only make sense to have the 16" wheels if you are a company car driver and it was going to reduce the benefit in kind charge and the VED as well as the fuel consumption. I suspect there is very little chance of the government allowing drivers to pay less tax as a result of changing the wheels on a car, so I opted for the 2 trim level with the published lower emissions figure.