Adam
I may be mistaken but my understanding was that the Gransport was released alongside the Coupe and the two were sold in parallel. Therefore this could well be a 2006 car.
Babster, issue for you is, which car do you prefer, the Coupe, or the Gransport? Main visual differences vs your Coupe are the Gransport gained side skirts, a rear spoiler and sports seats. It was also lowered slightly, gained about 5 horsepower and the exhast has a valve that opens when sport button is activated. I am not sure that the suspension differed in any other way.
If you buy the Coupe it may depreciate a tad faster than the Gransport as most people looking for a 2006 model will opt for the Gransport.
So is it actually a (more subtle) Coupe you want, or a (sportier) Gransport. Test driving each may help the decision process.
If a Coupe this looks a good example (subject to inspection of course, as Frank counsels) but prices seem soft at present and you may be able to win it with a cheeky offer. 2005 Gransport with 50k are fetching circa £24k these days.
Happy hunting
Cheers