For car camping, buy the thickest pad your trunk can hold

Yes, the answer is basically that.

Car camping means weight and packed size are irrelevant. You want maximum comfort. That rules out almost all backpacking pads. They’re designed to be small and light, not comfortable for eight hours on your side.

What you actually want: A thick, insulated pad with at least 3–4 inches of vertical loft. Think of it as a cheap mattress replacement. Your two winners in 2025 are the Exped MegaMat 10 (or the newer Duo if you’re sharing) and the Therm-a-Rest Mondoking 3D. Both are stupidly comfortable. The Exped is a bit warmer (R-value over 8) and packs slightly smaller. The Mondoking is plusher and has a better valve system.

Alternatives if you’re on a budget: The Klymit Insulated Static V is fine but it’s a compromise. Or just grab a cheap, thick foam pad from REI or Cabela’s. For car camping, the difference between a $60 pad and a $250 pad is mostly durability and warmth, not comfort – if you buy something thick enough.

One thing to avoid: Those self-inflating pads that claim to be 1.5 inches thick. They’re not thick enough. Your hip will find the ground by 3 AM.

If you really want to sleep well, just get the Exped. It’s the gold standard for a reason. Future you will thank present you.