Creating a Car

Now I have modeled a some type of objects to start using blender because I am new. I’ve created an Eyeball, a Building, a Sword, an easy Alien and now I tried to create a car.(An easy one).
I Started from a Cube, subdivided it 3 times and then started to make the general form of the car. :

My Question is, how can I create the Wheels for the car?

depends how detailed you want the car but have you tryed extruding a circle?

You can use cylinder for a wheel. The hard part is the wheel wells that need to blend in with the body. Here is my WIP on wheel well. I am still trying to figure how to reduce the mesh count and still have good form: