2010 BMW 1 Series | New BMW Convertibles The 2010 1 Series is a 2-door, 4-passenger luxury sports coupe, or luxury convertible, available in 4 trims,... read more ranging from the 128i Coupe to the 135i Convertible. Upon introduction, the 128i Coupe is equipped with a standard 3.0-liter, I6, 230-horsepower engine that achieves 18-mpg in the city and 28-mpg on the highway. The 135i Convertible is equipped with a standard 3.0-liter, I6, 300-horsepower, turbo engine that achieves 17-mpg in the city and 26-mpg on the highway. A 6-speed manual transmission with overdrive is standard on both trims, and a 6-speed automatic transmission with overdrive is optional. The 2010 1 Series is a carryover from 2009.