Best Car Camping Pad out there, period.
I own two of these... I have to fight my wife and son for dibs on these. No matter how cold it is, you are insulated from the ground and easily forget you aren't in your own bed at home.
Pricey... but worth it if you want ultimate sleeping comfort for car-style camping. (Warning: do not try to carry this as part of a multi-night deep woods hike... unless you plan to leave all your other gear at home. Additional Warning: you may be tempted to make this dangerous decision.)