Wrong,wrong,all wrong.The reasons our cars get worse mileage in cold weather are,it takes longer for them to get to operating temperature in cold climates,the denser air creates more drag on the outside of the car,and driving through water,snow,and slop,creates more drag on the tires.(Remember the last time you drove through a puddle in the road,you can feel the car slow down.)You will get better performance in cold weather because of the denser air but the ECM will set the fuel air mixture at the same value as hotter times of the year.This way you get more air and also more fuel.

 

is that not what I said? if you burn more fuel, your economy will go down. I'm pretty sure the original post meant in decent weather with similar road conditions. otherwise, you're correct. And cooler air isn't gonna make the drag on the car measureably different.

 

while we are on the subjuct how does the cai thing work. I thought metal conducted heat and rubber or plastic absorbed it so shouldnt metal keep the air hot when it goes through the metal cai pipe

 

they don't work.