Not that its a "must" to have the latest, but the T4 '15 should be out in less than 3 months.
I have the T4 '13 and there are some similarities. The Xrays is probably the most durable high end touring car available right now. Very low wear on parts as well. I'd like to see it have DCJ's equipped since a lot more cars are including them as standard now. Anyways, I just picked up a D06 and the quality is comparable. Quite a nice car.