Based on data from 4 vehicles, 37 fuel-ups and 14, miles of driving, the Mercedes-Benz R gets a combined Avg MPG of with a MPG margin of. The diesel version starts at $51,, but options made the as-tested price balloon to around $67, The R-Class' price range overlaps two of Mercedes' SUVs. Mercedes-Benz R-Class 4MATIC 4dr R Specs ; MPG, 16 City / 21 Hwy ; Body Style, Wagon ; Wheelbase (in.) ; Length, Overall (in.) ; Width, Max w/o.