My highest MPG I've ever gotten was 31.28, and that was pretty much non stop about 200 miles north and back. I average about 16 MPG in summer (I drive a Buick Roadmaster, Corvette V8 engine etc), and about 21 MPG in winter (small V6 engine, all city driving). I could only dream of numbers in the high 30s or 40s hehe.