First
In the beginning, God created the Heavens and the Earth. -Genesis
We will begin with the earth portion of that, and go from there.
The ground is an important part of the render, because it captures the light, and keeps the car from looking like it is floating mid air. The ground is also a decision factor in your render, do you want to focus attention to the model itself, or away from the model?
The more complex the background, the more attention it grabs, so often photography companies tend to keep the background as solid as possible without grabbing much attention (in photography, low f-stop lenses are used to blur out a distracting background)
Because 3d isn't real, you can do whatever you want, but lets begin with the basics of backgrounds.
Plane
Scene
The most basic of all, it extends to the edge of view, and just grounds the model itself.
Lighting
Always from above, and casts down on model.
Bowl
Scene
As common as flat plane is, however this doesn't have the sky/ground distraction flat ground is known to cause.
Lighting
Typically just from above.
Quarter pipe
Scene
This is the most common background, as it is very simple, very many variations of the quarter pipe, so it is very useful.
Lighting
Lights can cast downwards on subject, and towards the subject from 'outside'.
Box
Scene
Also very basic, however instead of having to worry about background, you now have a closed location.
Lighting
You can now control the lighting from anywhere, besides only on the ground, you can now light up a wall, the roof, etc.
Sphere
Scene
Fully inclosed, very similar to box, however, does not have wall edge issues boxes are known to have.
Lighting
Similar to box.
But what's the difference?
Well as you can tell by their shape there are plenty of differences!
Why choose one over the other?
Depends on what you are going for, if it's an outdoor scene, flat plain is the right one for you then!
Which is the best?
Well like I said, it depends on what you want to do, having all to play around with though is better than working with just one.
How do I make these?
Stay tuned and I will show you, we must finish the basics first!
Go out and experiment!