Normally, I would say that you should probably continue driving the car you have which would cost you nothing. On the other hand, this really is a good time to be a car buyer. There are fantastic used car and new car deals. Here, BMW is offering a $10,000 discount off the e92/e90 M3.
Personally, the unreliability of the Jaguar throws me off. Combine that with a lack of quality control, and it's not my pick of the litter (unless you're looking at the DB9 replica Jag-probably out of your price range).
An Audi A5/S5 is a pretty reasonable choice. It's a very luxurious, beautiful, and powerful vehicle. My biggest concern with a brand new Audi would be resale. If you can find it for the right price, then by all means go for it.
A Jetta TDI is pretty reasonable car, though a bit on the expensive side for cars in its class, and considering Volkswagen's reliability/quality control issues. Another concern I would have is the way the oil companies manipulate the cost of diesel. It's far less expensive to produce than gasoline, and yet it costs more? On the other hand, if you're the handyman/do-it-yourself kind of guy, you can go the WVO route and operate your vehicle at a far lesser cost.
WVO = Waste Vegetable Oil
If you have no idea what I am talking about, visit this site:
Greasecar Vegetable Fuel Systems