Find the best used Japanese premium car you can that has just come off a 3-4 year lease and has less than 30k miles on it. Look to Lexus, Acura, Infinity, etc. Alternately, you can also still find some values in off-lease BMWs, but expect higher maintanance costs. Use carfax to find complete history of vehicle.
I helped my gf find a 4 year old Infinity G30 with 28k miles, totally loaded with 3 liter engine, sunroof, leather, etc. for ~$17k last summer. Runs like a top. The used dealership we negotiated with pulled up the complete carfax report for us on the computer, and even showed us their auction invoice plus all reconditioning work they had done on it before putting it up for sale (changed the alternator, fixed a few minor problems, etc.). Most major cities seem to have a few good used car dealerships that specialize in off-lease premium vehicles. You can tell these by the fact that they usually ONLY have used premium vehicles (you won't find a used Taurus on their lot!) and have a large repair shop, and offer a decent warranty after the sale. We were able to negotiate up from his auction invoice, so we didn't discuss price, we disussed how much profit he was making. Everyone walked away happy...
FS