What is it about the specification of a 2009 car that represents an improvement or benefit over that of a 2007 car? Do these outweigh the factors that, as have been discussed, make the 2007 model a more desireable proposition - the bigger engine, for example?
Once you have quantified this, you will be able to determine the loss which you have experienced, and thus be able to seek compensation for this loss - although as 4/4boy has indicated. Otherwise, it just appears to be a wrangle about dates, with no material difference to the car.
