I have used the Thermarest and ended up happy as heck that I bought it from REI as they have a GREAT return policy. 1 use on a tarp and it was leaking! Ended up getting a Thermarest Ridgerest. Not as compfy but it doesn't deflate <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> Also for car camping I bought a foam pad from Fred Meyer that is 3in thick. Not compact but as close to a real mattress as I have ever slept on the ground on. Being closed cell foam it too will not deflate <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />