BMWs 2-seat sports car is a convertible with an inline 6-cyl engine and a standard manual soft top with heated glass rear window. A power soft top is optional. The Z4 2.5i has a 184-hp 2.5 liter, the Z4 3.0i has a 225-hp 3.0. The 2.5i comes with a 5-speed manual transmission, the 3.0i a 6-speed manual. Both offer two optional transmissions, a 5-speed automatic with manual shift gate or BMWs Sequential Manual Gearbox. This 6-speed sequential manual transmission (SMT) has no clutch pedal, shifts via the gear lever or steering-wheel paddles, and can be set to shift like an automatic. All models come with run-flat tires, ABS, and an antiskid system. The 2.5i comes with 16-inch wheels, the 3.0i with 17s. An optional Sport Package includes a sport suspension and increases wheel size to 17 on the 2.5i, 18 on the 3.0i. It also adds a Dynamic Driving Control console button that quickens throttle action and reduces power-steering assist.