It depends on which year of the car you want. A 2005 BMW Z4 Roadster gets 27 miles per gallon on the highway, and 18 miles per gallon in the city. A car that is more recent might have better fuel economy.
The EPA mileage estimate for the 2001 BMW M3 is 15 mpg in the city, 22 mpg on the highway.
The EPA mileage estimate for the 2014 BMW Z4 is 22 mpg in the city, 34 mpg on the highway.
The EPA mileage estimate for the 2002 BMW M5 is 12 mpg in the city, 19 mpg on the highway.
The EPA mileage estimate for the 2002 BMW X5 is 14 mpg in the city, 19 mpg on the highway.
The EPA mileage estimate for the 2014 BMW X3 is 21 mpg in the city, 28 mpg on the highway.
The EPA mileage estimate for the 2001 BMW X5 is 14 mpg in the city, 19 mpg on the highway.
The EPA mileage estimate for the 2007 BMW M5 is 11 mpg in the city, 17 mpg on the highway.
The EPA mileage estimate for the 2006 BMW M3 is 14 mpg in the city, 22 mpg on the highway.
The EPA mileage estimate for the 2013 BMW X1 is 24 mpg in the city, 34 mpg on the highway.
The EPA mileage estimate for the 2007 BMW M6 is 11 mpg in the city, 17 mpg on the highway.
The EPA mileage estimate for the 2009 BMW X6 is 15 mpg in the city, 20 mpg on the highway.
The EPA mileage estimate for the 2014 BMW M6 is 14 mpg in the city, 20 mpg on the highway.