Since you are selling it, you don't care about durability. Thus, NXT 2.0 will work fine for you. It's easy on -- easy off, but will stain trim. It's somewhat pricey for it's performance. In order to answer your question, more info would help:
What condition is the paint in? Swirls/scratches? Faded? Near perfect? Color?
Anything you grab off the shelf will probably make it look better.
If you have a Big Lots, try 3M Performance Finish for $3. If you want to go all out, try AutoGlym Wax from Walmart for $35.