I would not mind paying if I had some share with the oil industry! I just say that they could come up with a more efficient engine in a small RV, like they do in Europe.
I remember a few years ago, my 2002, 2 cycle snowmobile was sucking around 6 MPG. Then came the 4 cycle engine, I bought a 2008 and was doing around 15 MPG. Then pure magic, in a short time, they came up with a much more Horse power 2 cycle engine and now get around 16 to 18 MPG with a 2009 SkiDoo. Except for a better ride comfort and performance, no big weight difference between the 3 models with weight, wind resistance, track or skis.
They did it when they where pushed by the new antipolution rules. I am sure they could do better but they will not until they loose money or they loose the market.