How long can a car stay in garage if temps drop below freezing

Just went back to the shop(11 at night). Walked in that bay, bet its 50 in there, 33 outside. Was 69 inside the showroom, obviously some of that heat seeps through the one common wall.
Lot warmer than i thought it would be, way warmer than outside. Put a heater in there anyhow, just to be sure.