I'll admit my experience with road salt and heated garages came from watching a Porsche 911 rust away before my eyes....eventually you could see the road pass by under the floor mats! Hopefully , MBs are built of stronger stuff. ****E, Porsche built my E500!
FWIW, up here at the 53rd latitude, we use road salt for 6-7 months of the year and its commonly accepted that garages heated above zero will accelerate rust.