Originally Posted by XsteveedgeX

So basically stock 2008 jku, only mods are a smittybilt rear bumper and a body armor roof rack base. I was still at at least 19mpg. Now that it got cold BAM! I am lucky to be getting 17mpg. Any ideas why? Is this normal? I put new plugs and air filter in it and no change. Thanx for any suggestions...