A sponge isn't ok but a 100PSI jet of water is!? Interesting.
The problem with an automated wash at this time of year is the pre-wash stage won't remove much of the dirt before the brushes are applied, so you've got brushes that aren't particularly kind hitting paintwork that still has dirt in it, which is a recipe for disaster.
The best method at this time of year is to snowfoam them pressure wash off. If you're concerned about leaving pools of water on your drive then it's probably too cold to be washing your car anyway!
I think what people often forget is that these cars were continuously tested at sub-zero temperatures for months. Not washed them one week really won't do any harm.