Mine is a standard. I skip gears and short shift a lot also, but not for efficiencies sake, just driving habit.
You got some impressive mileage on your trip.
The Jettas get slightly better mileage than Beetles from what I have read and the Passats are supposed to be better still. I also have the rag top (almost always down) with the wing, so my aerodynamics aren't the best.
I have heard temperature affects the mileage also. I have only had my car since last fall, so I can't say yet if I will see improvements in warmer weather.