Strap the cooler body, not the lid.

Ratchet straps are overkill for a cooler, and yes, they can wreck the lid. The right move is strapping around the cooler’s body, not over the top, and keeping it snug enough that it can’t slide — not cranked down like you’re tying down a dirt bike.

Most cars have tie-down points in the trunk: D-rings, cargo loops, or sometimes just the metal loops near the seatbacks. Use those. If you don’t have any, run a strap around the base of the rear seat or hook it to the seat anchors under the trunk floor. The goal is a low anchor point, because strapping to the lid pulls it off.

Cam-buckle straps are the sweet spot. They’re easy to tension, release quickly, and won’t over-compress the cooler like a ratchet will. A ratchet can bow the lid, crack the hinges, or pop the latch over a long drive. If a ratchet is all you have, stop tightening the moment the cooler stops moving — don’t crank it one more click.

Also worth doing: put a rubber non-slip mat under the cooler, or just wedge it tight against the back seat.