There's a technique call Pulse & Glide that usually allows you to increase your mileage by a good chunk if used properly. Essentially, it takes advantage of the increase in gasoline engine efficiency under load, and the beefy stop-start system and electric motor that hybrids have. This is a time honored technique, used since the earliest Shell mileage competitions and it's based off of a simple idea. By accelerating quickly to some speed, say 45mph, then coasting back down to another speed with the engine off, maybe 30pmh, the driver gets the advantage of driving at an average speed of maybe 37mph, while engine efficiency increases (maximizing hp~minimizing pumping losses) compared to driving at a steady 37mph. P&G'ing with a hybrid is nice because stoping/starting isn't as much wear on the vehicle since it's designed for it, and the electric motor allows a reserve of power to use without turning the engine back on so the driver can optimize the glide phase for efficiency. A great write can be found
here. Hit me up if you have any questions, or better yet, join the cleanmpg forums.