i here ya but think of it this way when u entering a turn and your like 20 feet away lets say and u got a car like the 4 that didnt roll as free its like using drag brake so now at the 20 foot mark with a 5 u can let off the gas and carry the same speed and roll around the turn but with a 4 i had to stay on the gas till 5 feet away im just using numbers to make my point but u get the the point that 15 foot diffenance of off gas speed every turn every lap is going to save u a hell of alot of gas.. and yes i beleave what u saying bout setup clutch etc. playing a part as well, but i been making runtime stright out the box with the 5 when the setup was not even half as good as my 4 untill i had time to learn the car and the rear was spinning and sliding everywere and i made run time...