First, I am assuming that you are in the United States.
I think loans to buy depreciating assets for personal use are a bad idea. Hence, I would avoid them. You seem to be doing very well financially. If I really liked an Audi I would look to buy one used and pay cash. I would then safe up enough money to buy a new or slightly used Audi. At that point you could buy the car you really want or want until your car had to be replaced. The second would result in a larger retirement nest egg.