BMW's 2-seat sports car deletes a transmission option on its base model for 2005. The Z4 is a convertible with a manual soft top or optional power soft top; both have a heated glass rear window. Two models are offered, both with an inline 6-cyl engine. The Z4 2.5i has a 184-hp 2.5-liter, the Z4 3.0i has a 225-hp 3.0. Manual transmission is standard; a 5-speed on the 2.5i, a 6-speed on the 3.0i. A 5-speed automatic with manual shift gate is optional on both. BMW's Sequential Manual Gearbox is optional on the 3.0i and no longer offered on the 2.5i. The 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 Z4s have 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 17-inch wheels for the 2.5i, 18s for the 3.0i. It also adds Dynamic Driving Control in which a console button quickens throttle action and reduces power-steering assist. Leather upholstery is standard on the 3.0i, optional on the 2.5i. Heated seats, xenon headlights, a navigation system, and BMW Assist emergency and concierge service are optional. BMW says a Z4 coupe and freshened convertibles will arrive as 2006 models later in the model year.