Free

Just Good Cars - New and used car classifieds. News, car search, and form to sell a car.
http://www.justgoodcars.com/

Kakagua.com - Used cars for sale by owner in the United States and Latin America.
http://www.kakagua.com/index_eng.php

AutoDirection.com - Auto ads from individuals and dealers.
http://www.autodirection.com/

Car-Sale.org.uk - Used car classifieds for the United Kingdom.
http://www.car-sale.org.uk/

Autop10.com - Identifies the ten cheapest classified car ads based search criteria. Inventory, blog, and form to sell a car.
http://www.autopten.com

Wheelbynet.com - Auto, boat, motorcycle and rv ads sorted by type, make, area.
http://www.wheelbynet.com

Vehicle Trader - Used car classifieds for the United Kingdom. Place and manage an ad.
http://www.vehicle-trader.co.uk/

Auto Explosion - Searchable used vehicle database, consumers may post free ads with photos.
http://autoexplosion.com/

Cardealer.com.pk - Buying and selling tips, special offers, and car maintenance information. Pakistan.
http://cardealer.com.pk/

Auto101 - Searchable database of vehicles available from private sellers.
http://www.auto101.com/

Aloha Auto Search - Automotive ads from dealers and individuals.
http://classifieds.speedhawaii.com/

CarBarter - Free car classifieds for Australian dealers and citizens. News and car reviews.
http://carbarter.com.au/

CarMarket - Provides compact, tabular list of cars for sale.
http://www.carmarket.com/

Preowned Car Classifieds - Used car news, post a used car classified ad, and browse cars for sale.
http://www.preownedcar.com/