I need a camera to view cars at approx 35 - 40 m from camera and approx max 12 m wide at the 40m.
What is the best option and is the lens right for my application?

You would need a 15mm lens on a 1/3" camera or a 11mm lens on a 1/4" camera. The easiest way to get the exact field of view you want would be to use a varifocal lens or buy a camera system that has a varifocal lens. Your best bet there would probably be a camera with a 5-50mm lens.

If you need to see the cars in low light, choose a true day/night camera with an auto-iris varifocal lens.

Previous answer is correct, but strictly speaking you should also consider camera installation height.

For example, if you put camera on 25 meters pole you will get
18 mm for 1/4" camera
and 12 mm for 1/4"

It is very easy to calculate lens and FOV using CCTV Design Tool