Too many factors to give a be-all, end-all answer, including year and make, engine, gear ratios of transmission and rear ends, tire size, terrain, load weight and profile, etc. Volvos with the Volvo engine are traditionally good for mileage with optimal aerodynamic loads, such as a tanker or van trailer, but not so much for open deck trailers.. I've reports of 8+ MPG average, but I certainly never saw it pulling an RGN with a Volvo.
Four to nine MPG, depending on a number of factors. It's pretty much the same with any tractor trailer.
3-6 mpg
20-23 mpg depending on how and where you drive.
You can expect 20-23 mpg depending on how and where you drive.
Between 2 and 10 MPG depending on load, road conditions and speed
second Question has better information Aerodynamic Cab 600hp Caterpillar Tractor Engine with Eaton 13 or 18 speed Transmission
Many of the new large displacement (15L) are running 5 -6.5 mpg at 80K some of the smaller displacement (9L,11L)get up to 8.5mpg at 40-60K
The EPA mileage estimate for the 2013 Volvo XC60 is 19 mpg in the city, 25 mpg on the highway.
The EPA mileage estimate for the 2009 Volvo XC70 is 15 mpg in the city, 23 mpg on the highway.
The EPA mileage estimate for the 2006 Volvo C70 is 18 mpg in the city, 26 mpg on the highway.
The EPA mileage estimate for the 2014 Volvo XC70 is 18 mpg in the city, 26 mpg on the highway.
The EPA mileage estimate for the 2009 Volvo S60 is 19 mpg in the city, 28 mpg on the highway.