subject: Most Popular BMW Is The 2010 BMW Z4 [print this page] For those who want a bit more acceleration and speed from their BMW Z4s, there is a second engine option: The turbocharged 3.0 liter inline-6, featuring 300 horsepower and 300 foot-pounds of torque. This is exactly the same engine found in its BMW 335i cousin, and is no less riveting. With peak torque found at a lazy but impressive 1400 RPM, fuel economy is preserved throughout a wide range of speeds. Expect 18 mpg city, 25 mpg highway from this brute.