Welcome to being retired. You will love it.

Drive both. I think you will find the T-bird to be much more comfortable. As I get ollder I find out that I have a 2 hour a** in all my sports cars but I can extend the range to 8 plus hours in my normal cars -- Mercedes.

This seat time comment is no slam on the Xfire just seems to be true at least for me. My wife hates all the sports cars; she prefers her Mercedes. I do find the seats in the Xfires to be less then comforable by comparsion to my other Mercedes.

My current sports cars are a Triumph TR3A, TR6, Xfires (roadster and coupe) and Austin Healey 3000. My next one is going to be a Morgan. Honestly I do not see that much difference in the seat time except for the nicety of cruise control between all these cars. On the fun meter NOTHING beats the TR3. At eighty it feels like you are going 120 plus. There is something to be said for being 6 inches off the ground and the cockpit door only being 15 inches from the ground.

Maintence I believe it is a draw. However body parts for the Xfire can be difficult but check out the T bird availablity of parts. I do believe unless you do your own work, it may be hardier to get the Xfire fixed with a real complex problem. The software requires access to the Mercedes equipment. Mercedes parts are not cheap.

Get a low mileage, one owner car in either case.

Hope this helps.

PS If you elect to own a Xfire may I suggest a roadster over a coupe. Remember I have both and the coupe has nicer lines BUT the fun of driving with the top down is PRICELESS.