It's really weird. The salesman told me the same thing though.....he said on the highway, it'll rival my Scion as far as fuel mileage, but around town, be really light on the gas because it's going to suck fuel. He said that it's because it's got a lot of power and a tall highway gear, it doesn't take much to keep her going on the highway.
Gotta say, it's nice driving the automotive equivalent of the Santa Fe Super Chief on the highway, as opposed to the buzz of a 4 cylinder