The 2007 BMW Z4 is available as a 2-door, 2-seat convertible. Starting at $40,400, the 2007 BMW Z4 Coupe is powered by a 3.0L, 6-cylinder engine mated to a manual transmission that returns an EPA estimated 20-mpg in the city and 30-mpg on the highway. The top of the line 2007 BMW Z4 3.0si Roadster, priced at $42,400, is powered by a 3.0L, 6-cylinder engine mated to a manual transmission that returns an EPA estimated 20-mpg in the city and 30-mpg on the highway.