IMO, being flippant about the efficiency of the motorhome because they all get poor mileage is short sided. What if it only got 2 mpg? How about 1? What if you had to stop 4 times a day to fill the SOB up? Absolutely efficiency matters. And costs matter as well. I live rurally, and I bet that I wouldn't miss it much if I said our fuel costs weekly are an average of $250. That's $13k a year to the oil companies. Does it matter that 15%(or more) of the mpg have been sucked out of the fuel? To me it sure does!