I used a "Carcoon" for a number of years - was very good at drying the car if wet and I had no problems with it at all - I would definitely recommend one - you do need an electrical feed to power the fan - you drive on to the base and Zip on the cover which when the fan is plugged in inflates over the car - only needs a space slightly larger that the footprint of the car
Survived the Irish Rain storms!!!!
Cheers!