My LeMans currently has it's original 326 w/62k original miles. It currently has an alluminum intake and an Edlebrock 1406 mounted on it. When I had the 2-speed auto trans w/ the original 2.56 open rear I was getting 20.5mpg. Not that I have done the 4-speed swap, much to my surprise I am now getting 22.75mpg! I can not beleive these old cars can get such excellent gas milage, it blows my mind!