For the last several years I have been using X-treme clear by Five Star. It sprays nice and dries with a glassy finish. I painted my old Nissan Sentra with it (used over DuPont Chromabase) about 6 years ago. This car sits outside in the hot sun (that's very intense here in Florida), the rain, etc. 365 days a year and has never been waxed or polished in all that time. It is just now starting to oxidize on the roof. The paint would undoubtedly last longer if I had taken care of it, but I wanted to see just how it would hold up. This stuff costs about $85 for a gallon of clear and a quart of catalyst (5 quarts sprayable).

I have also used Transtar with good results and durability comparable to the Five Star.