Quote - How exactly do you want to use the car? As a background.. like a poster on some wall? Do you mean an actual photo, or a render of a car model?  This is interesting because I have always wonder about this if one day I do something using some model like a car.

Sometimes when I'm in a shop that has Posters, I find posters of popular Cars and it got me thinking. 

What if I were to render lets a picture of a beach with a well known car in it and decided to sell that picture online.  Would I get in trouble? And from what everyone has said here sounds like I would.  But I also wonder how many of those poster pictures were actually cleared with the manufacturer.

And come to think of it, I guess it applies to everything.... What if I did a scene of  restaurant and had  a can of Coke or Pepsi on the table.  Would I get in trouble selling the image?