Snow does not cause rust, and neither does salt.
BUT, salt mixed with snow that then melts *does* cause rust.
So ... avoid driving in salt, and avoid driving in snow.
Given that that's not too likely, then don't let the snow/salt mixture melt on your car (e.g. don't park your slush-covered car in a heated garage for the night, because the slush will melt and start the rusting process. So long as the snow and ice doesn't melt, rust won't start).
Failing that, just be very vigilant about hosing off your whole car, but especially the wheel wells and the rest of the undercarriage, on a daily basis.
The good news is that we all have plastic liners in our wheel wells (about bloody time the auto makers did that).
The bad news is, this simply means that there are all sort of hidden places where rust can start and you won't see it.
So, wash your car as often as possible.
BUT, salt mixed with snow that then melts *does* cause rust.
So ... avoid driving in salt, and avoid driving in snow.
Given that that's not too likely, then don't let the snow/salt mixture melt on your car (e.g. don't park your slush-covered car in a heated garage for the night, because the slush will melt and start the rusting process. So long as the snow and ice doesn't melt, rust won't start).
Failing that, just be very vigilant about hosing off your whole car, but especially the wheel wells and the rest of the undercarriage, on a daily basis.
The good news is that we all have plastic liners in our wheel wells (about bloody time the auto makers did that).
The bad news is, this simply means that there are all sort of hidden places where rust can start and you won't see it.
So, wash your car as often as possible.