i saw the movie, but the film was so cheaply made that I highly doubt its a real one. I mean honestly, just look at some of the props, the Lambo real or fake was probably the most expensive prop. Although, I am usually wrong on these types of things!
My friend had a bit part in that movie. He was the personal trainer "Pete" next to the treadmill. They shot that movie over 3 years ago and shelved it. They didnt want to release it right away, they wanted to make Jack Black a bigger star with other movies before the release of Envy thus makeing it a more profitable film.
Sorry dont know about the car. I'm sure it was real.