This is a paid asset, but now you can download 2d cars (72 types) Free.
Detail this asset from Unity Store: Original Link
2d cars (72 types) v7
72 cars with 18 wheels for use in side scrolling driving games, wheels are interchangeable. For use in games like hill climb racing. Now with 9 different racing car skins. SUV’s, Policecars, Ambulance, Icecream van, muscle cars, japanese sports cars, offroaders, buggy’s, School bus, milkfloat, pickups, vans, hotrods, bubble cars, stock car, hot hatch, monster truck,formula racer, taxi, cabs and super cars, a big variety of cars, most cars have 2 skin types. Artwork provided as high res for use in both desktop or mobile games. All cars are based on 512/256 textures, uncompressed.