I don't own one, but almost any car is fine for track driving and the small dunes. However, the lousy departure and approach angles and low clearance on your car will be an issue on any higher dunes or uneven terrain. If you're careful it won't be a problem, but one mistake and you could end up with substantial damage and a huge repair bill.

My reccomendation would be to buy an older car (Nissan Patrol, pre-1998 Toyota Land Cruiser, Jeep Wrangler or Cherokee, etc.) to use in the desert and leave the shiny soccer-mom SUV at home ;)