Very little because I dont push it so I can say I run this fast or that fast. I usually run 3.7 to 4.0 with very very little loss and I know a R72 has more capacity. The only reason I responded is because who ever says a speed or a yeild or anything else some one will come up with some thing bigger or better so whats the point in saying how fast you run its all about how much you dont leave.