I've never had good luck selling something big like cars. I've had cars for sale on craigslist for a combined year at least and never had a sale result from it. Only had about 2 emails, neither resulted in a test drive. Seems like the people that are in the market for the kind of cars I'm usually selling, don't use craigslist to find them.
For other stuff it's not bad. I sold a Yamaha DT50 enduro in about a week. I've got a Washburn Dimebag Darrel signature guitar on there right now and haven't had a single hit though.