Well it seems to me like all of the photos of devastated homes still show the cars in the garage with the debris on top of them. I would argue that if you live on a slab home as I do, and if the storm devastated the house, being in the closet wouldn’t help much. I would also argue that if the storm could suck up the car it would certainly more easily suck you from your closet.
I look at it this way. If I’m in my Suburban in my garage I have two levels of protection, the car and the house. How does anyone think a 4000 lb car is more likely to be sucked from a garage than a 200 lb man from his closet?