When did the motor tax rates change in 2008 from engine size to emission based?

See here. The good news is you choose! If the motor tax for a Mar 2008 registered vehicle is cheaper based on engine size or emissions, its the cheapest of the 2 for any car in that 6 month period Jan-June 2008. Check out the motor tax based on engine size here and emissions here. For an imported vehicle you can choose which amount you want to pay. Like I said, good news!