What's also important in that Budget Report quote is the March 2010 date. That means if you buy a £200 car today, you can't just convert that into a £2000 discount on a new car in 1 year, since there are only 11 months remaining in the year. You need to own the car for 12 months to take advantage of this deal.
Sneaky....
The devil's in the details - as always.