We are making a game filled with thousands of cars. We were wondering if we need a licence to use body designs of lets say a Lamborghini, Ferrari, Impala. etc. We do not want to pay money to use the designs in our game, of course we are going to make our own car brands though. Can we use a similar body design??
Technically, the design is owned by the company as well. Now, depending on how realistic the game is or how many details you can see about the care, it might not matter at all.
What is important is not to use any distinctive symbols that appear on the car, or any actual names. There are many games that make cars that only look like the original ones, but give them different qualities (like, top speed, sign, name) so that they won't infringe any copyrights or trademarks.
Here is also a nice article on this subject: http://www.giantbomb.com/fictional-car-brands/3015-5156/
One of the best seperators between real cars and toy cars, is in my experience the shaders.
I've spent quite some time with BMW, where we needed to hit the exact glossyness, reflection and feeling of one of their chrome textures.
Without it, the car looked like a small plastic toy, but once it got on, the whole imagry changed, and the car turned into a "believable" vehicle.
Also, use of camera is important here as well. Notice in both car games and especially car ads, how they portray the car to make it look big and robust. In reality, cars aren't that impressive in size, but they always manage to make that feel to it.
And last, but not least, make sure it FEELS like a car. The audio, the steering, the way it moves in place when you hit the brakes. The feel of an object is the final touch in making it feel believable.