[Matra et Alpine]

The Carcoon's are fine.
The only drawback is that you have to pull the cover over, zip it and then inflate. So it can make it a real pain to do on your own.
Others do similar with a frame ... but because of Carcoon's patent none of them were able to do the air circulation !

THAT makes a big difference. I can put the car in wet and within a couple of hours it's dried out

It's too much hassle for storing "normal" car/bike I'd say. But if storing for long periods it's a real winner.