You can see examples of Virtual Objects on my website www.arev.photographer.org follow the link to Virtual Objects. It works well but as you will see the movement isn't particularly smooth when you want to keep file size down to a minimum. I've had little call for it commercially but it is fun.
For large objects like a car, you need to make a circle! Use a piece of rope and a peg hammered into the ground. walk out the required distance and then using either paint, sand, flour walk around in a circle dropping or painting the ground.
Once this is done and you have a perfect circle, stand on the circle and take your photos! (Make sure you put the car inside the circle ) Make it even better by making it into a "pie chart" this way you also get the "even" positioning points where you need to stand for each photo/image to be taken.
Hope this helps, Smooth