The Z4 is available as a roadster with a convertible top or as a fixed-roof coupe. The roadster comes in two trims, the 3.0i and the 3.0si, while the coupe is available in 3.0si trim only. The 3.0i trim is equipped with a 215 hp 3.0-liter inline six-cylinder engine, a six-speed manual transmission, 17-inch alloy wheels and leatherette upholstery. The 3.0si trim boasts a 255 hp 3.0-liter inline six-cylinder engine, leather upholstery, automatic climate control and a THX Certified premium audio system. A six-speed STEPTRONIC automatic transmission with steering-wheel-mounted shift paddles is available on all Z4 trims. For 2008, Stratus Gray Metallic replaces the Silver Gray Metallic exterior paint color from 2007, and the Sport Package now includes 18-inch wheels. Otherwise, the BMW Z4 carries over unchanged.