Rolling shots and Rig shots are different things.
Rolling shot is shot from one car to another. Here is one I took yesterday morning.
Cadillac CTS-V by -mik3ymomo-
A rig shot you need a rig. The one I have is from Rig Pro. They have a Facebook site. A guy named Andrew owns the company and makes the rigs. The technique requires photoshop to remove the rig.
The car is not running or driving and is rolled slowly while the rig is attached. A long shutter speed is required to give the effect.
Here are examples of Rig shots I've taken.
Range Rover Sport Supercharged rig shot by -mik3ymomo-
E92 M3 Rig shot by -mik3ymomo-