[aerohead]

All trucks are different.In the aggregate,gate up is better,but so little different that unless very careful at the pump,you'd never know.GM has a patent for 1/2 tonneau ( back half only ),they say its as good as full cover.Ford research shows otherwise.I know that a 1/2 tonneau works on Toyota,Dodge,Chevrolet,and Ford half-tons.Figure on about 5% mpg improvement.