[redpoint5]

Welcome to posting on the forum, and interesting first post.

In my experience there isn't a lot left on the table when a vehicle is a hybrid. It has a tendency to compensate for the inefficient driving practices of regular drivers that hypermilers have learned to overcome.

My Prius plug-in is rated at 50 MPG for either highway or city driving. I get 50 MPG in it (with tires I didn't choose, so that could be a factor). The Ford Fusion hybrid is rated at 42 MPG combined. When I rent one, I get 44 MPG.

My guess is that the greater of the two MPG ratings is about the best one could do unless employing extreme techniques, or simply driving much slower than the typical driver.