Under my rubber mat??

This stuff is what 74Sport is talking about.
It's HVAC duct insulation that comes as a big roll for commercial Heat and ac businesses.
I use a peice of it cut to fit my windshield for blocking the sun when the car is parked.
http://www.google.com/imgres?imgurl=http://www.tvmi.com/elements/production/217.jpg&imgrefurl=http://www.tvmi.com/prod_detail.php%3Fm%3D%26mm%3D%26t%3D0%26an%3D%26a%3D%26am%3D%26p%3D217&usg=__QiPkt9BqU8AAEaZh1JCCPXE9qu4=&h=210&w=210&sz=10&hl=en&start=229&zoom=1&tbnid=PkELX17_FN5-PM:&tbnh=106&tbnw=106&ei=BucsUJTyFoKCyAHS34GwBQ&prev=/search%3Fq%3Dhvac%2Bduct%2Binsulation%26start%3D220%26um%3D1%26hl%3Den%26sa%3DN%26gbv%3D2%26tbm%3Disch&um=1&itbs=1