Heated tunnel water
A wash tunnel running cold water in February will actually freeze on contact with the car — useless and potentially damaging. Modern soft-touch tunnels use heated water (typically 30-40°C) that cleans effectively in deep cold without freezing on the vehicle.
Underbody spray
Road salt accumulates on undercarriage components — brake lines, fuel lines, exhaust mounts. A car wash that doesn't include underbody spray is leaving the most-corrosive salt deposits in place. Look for packages that explicitly include underbody spray (Lava Shine and Rim Lovers tiers at Popular).
Clear-coat sealer wax
Sealer wax creates a thin hydrophobic barrier on clear coat that helps shed water + brine before they sit. Renewed each wash, the barrier is what keeps clear coat from etching over a single Canadian salt season.
Effective dryers
Wet door seams in deep cold = frozen-shut doors. Quality tunnel dryers leave the car at ~5% surface moisture max — light enough that residual seam moisture evaporates rather than freezes. After a winter wash, open + close each door once before parking the car for the day to break any thin ice that does form.