You'll probably find that on your logbook the co2 g/km emissions. any car registered from 2001 is not classed under their engine size but by there emissions. If your car is sprts rated in any way ( higher gear ratio) then you emissions are higher. I had a 2001 y corsa 1.4 SRi which was the same. The next release of the corsa after that the emissions had been lowered.
I spoke the DVLA and they said that I would have to write to the car manufacturer to ask them to re-check and re-register the emissions. I couldn't be bothered with that.