We're actually doing PPC now for used cars. The PPC ad is generated by our inventory feed. So, if we have, say, a 2005 Honda Accord LX in inventory, and someone performs a search for "2005 Honda Accord LX," our ad appears prominently. When clicked, you're taken to that unit's VDP page on our site. It's been quite a nice surprise, BIG lead generator, 120 days or so into it now.
We've done quite a few landing pages over the years for various events -- not necessarily PPC, but events, re-targeting, BT, etc. Two pieces of advice:
1. Coordinate your message and the landing page. Make sure that the page delivers the next logical step in the client's progression. In other words, if you are saying "Click for a Quote" and you land them on a fluff piece about why your dealership is so great, look for high abandonment rates. Make it easy for the client to find what he/she wants and to follow the next logical step.
2. Don't cheap-out on the page. If you have good tools on your site that have a high engagement level, get them on your page too.
Good luck!