My rig is a pretty modern Ford V10 based gasoline chassis. It gets 8-11 MPG, depending on how fast I'm driving, the weather, and whether I'm going over hills or not. Towing a vehicle behind will effect mileage. But, speed is the biggest determinant of mileage.
The big diesels tend to get about the same mileage. There are some little turbo diesels built on Sprinter chassis that get up to 17 MPG.
The old (ancient) diesel rigs I'm looking at to replace my current motorhome will get about 7-10 MPG, but can be converted to waste vegetable oil, or run biodiesel. So...maybe environmentally acceptable, as long as I don't put a lot of miles on it (I tend to like to travel for short distances at a stretch anyway, so I don't drive a huge amount of miles in any given month...much less than someone commuting 20-30 minutes to work every day would, for example).
I've talked to people doing it in the US, Canada, Europe, and Australia. I've met people from dozens of countries travelling the US this way. Germans, in particular, seem to be very interested in RVing in the US.
The big diesels tend to get about the same mileage. There are some little turbo diesels built on Sprinter chassis that get up to 17 MPG.
The old (ancient) diesel rigs I'm looking at to replace my current motorhome will get about 7-10 MPG, but can be converted to waste vegetable oil, or run biodiesel. So...maybe environmentally acceptable, as long as I don't put a lot of miles on it (I tend to like to travel for short distances at a stretch anyway, so I don't drive a huge amount of miles in any given month...much less than someone commuting 20-30 minutes to work every day would, for example).
I've talked to people doing it in the US, Canada, Europe, and Australia. I've met people from dozens of countries travelling the US this way. Germans, in particular, seem to be very interested in RVing in the US.