Rust inhibitor in the Luxury Wash
A rust inhibitor is applied to the underside.
What this stage does
Car wash rust inhibitors generally leave a thin film that helps keep water off exposed metal for a while after you drive out. In the Luxury wash it follows the under-car spray, so the salt is rinsed off before anything goes on.
Be realistic about what it is. It’s a top-up between washes, not a substitute for proper rustproofing, and it won’t undo rust that’s already started.
When it matters: Most useful during salt season, especially on older cars and trucks with exposed frames.
Luxury