This is a quick tutorial that explains all the process to make this composition. We're going to see how to make the model, materials, lighting, render parameters and finishing the image with Photoshop.
Modelling the bodywork
This model has the minimun polys possible and a "Mesh Smooth" modifier applied to smooth the surface. To start, I put reference pictures of the car in the scene. In this case, In the first place, I modelled the right part of the car in plane. I did it extruding edges. After that, I moved vertex to set up the volume. When I finished this, I started with the back side of the car in the same way. The complete process can be seen in this animated image.
To obtain soft edges, you have to "Chamfer" this edge. If you don't make this, the meshsmooth modifier will smooth this part.
To obtain sharp edges, I work with "Smoothing Groups". You have to give one "Smoothing Group" to one face an another different to the other. And don't forget to active the "Smoothing Groups" switch in "MeshSmooth" modifier..
To obtain hard angles, you have to "Chamfer" the edge or vertex of this angle. If you don't do this, this angle will be curved in the "Mesh Smooth" modifier.
Modelling the tires
Use a picture to reference. Extrude the faces to make a segment of tire.
Create a cylinder with the same radius of final tire.
Increase the sides of cylinder until every face measures the same size that the created piece of tire.
Copy the segment as many times as sides has the cylinder.