There's a discussion going on with Andy Tudor about box art. Below is a selection of existing racing games along with some community- (and Andy)-submitted box art concepts.
http://i183.photobucket.com/albums/x152/aleistad/Private/all_boxes_zps8bedc26e.jpg
Which ones do you like? There was one I liked a lot but in that grid it doesn't stand out nearly enough. If you want to make your own go ahead, I can post it at WMD for you (will link back here for credit) if you don't have access.
WMD Forum!