The thing is... conservation of energy. Unless the electric motor is more efficient than the gas engine, or charging the battery is "cheaper" by a lot than moving the car, the only way you "win" (aside from turning off stuff like the A/C) is to recapture as much energy as possible to the battery. If the battery charged itself off solar power, for example, it would be different, but trying to force use of the electric motor is just robbing Peter to pay Paul; you'll need to charge it later using the gas, and that appears from observation to be pretty expensive (Anyone have the numbers to compare? How many MPG is one bar on the battery on the flat at steady speed? How many miles can you go at steady speed of, say, 20mph on one bar of battery?).
Now if you can figure out how to get it to the top of a hill on battery only and then let it charge on the way down using only regenerative braking, you might have something....
Just like everyone else, I play the video game... I switch a lot between Energy and Comsumption... and the only secret I've discovered is that a slow steady pace wins (DUH) and I do better going to work (downhill) than coming home. It's really pretty slick, the car makes pretty good "decisions" on its own. Until the batteries hold a lot more potential energy and charge from additional non-gasoline sources I don't see doing much better.
Next time you are on a wide-open rather flat stretch of interstate try going for 20 minutes at 70 mph and then 20 at 50 mph. Now THAT is a measurable difference in consumption (not that one can necesssarily bring oneself to drive that slowly as a matter of course, but it IS educational). Also, the cold engine is clearly a lot less efficient. Even with it in the 80s outside that first 5 minutes costs.
But you know... 45 mpg really doesn't suck.