? If you are in the UK, AutoTrader looks like it would be helpful. It started as one of those free shopper magazines that you find on racks at the supermarket but has expanded to include a website and now a mobile site at autotrader.mobi. The mobile version lets you search a database of over 400,000 vehicles for sale by make, model and postcode. The site is free to use for buyers, no registration is required and listings include the seller's contact information.
To place an ad you will need to visit AutoTrader's full site at autotrader.co.uk Ads are not free. Prices range from 9.99 for a 2 week online-only (including mobile) listing of a vehicle priced under 1000 to 44.00 for a 3 week listing of a more expensive vehicle with the ad appearing simultaneously on the web and in the print magazine.
There's an AutoTrader in the US too. It's under different ownership but uses the same business model as its UK names with a free shopper magazine and a web site (AutoTrader.com) but no mobile presence that I could find. Opportunity lost for AutoTrader.com. Especially as two of it's US competitors are on the mobile web; Vehix Mobile and Cars.com Mobile
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