Isnt that something to do with the age of the car? The emissions thing is limited to cars built within the last x number of years....
The rules change depending on the age of the car.
I think it's before March 2001 it goes on engine size.
After that it goes on CO2 but there is something about the mega bucks band G only applying to cars built after March 2006.
Stupid thing about all this is, the Mrs and I try to use public transport but there isn't the infrastructure in the U.K. to stop people using cars.
The Mrs gets the train everyday and has to squeeze on the train as it is overcrowded, some people can't even get on.
I had to stand all the way from Birmingham to Leeds a few weeks ago as the train was overcrowded.
Also paid £1.80 or something silly for a 2.5 mile bus journey recently...