New styling and features, plus more V8 power, highlighted BMW's redesigned 5-Series for 2004. Gone was the wagon body style, leaving sedans that were slightly larger than the 1997-2003 models. BMW competed against the Audi A6, Lexus LS 430, and Mercedes-Benz E-Class sedans, along with the Acura TL/RL and Infiniti M. Four models were offered: 525i, 530i, 545i, and 545i 6-Speed. The 525i retained a 184-horsepower 2.5-liter inline six-cylinder engine; the 530i carried over a 225-horsepower 3.0-liter inline six. Both 545i models used a 4.4-liter V8 that produced 325 horsepower, up from 290 in the 2003 540i. The 525i, 530i, and 545i 6-Speed came with a six-speed manual transmission. Standard on the 545i and optional for the 525i and 530i was a six-speed automatic with manual shift gate. All 5s had BMW's iDrive, which used a console "joystick" to control entertainment, navigation, communication, and climate functions. Antilock braking, BMW Assist emergency and concierge service, a tire-pressure monitor, and traction/antiskid control were standard. Front side airbags and front/rear head-protecting tubular side airbags also were standard. Rear torso side airbags were optional. The 545i 6-Speed had a sport suspension, run-flat tires, and BMW's Active Steering that electronically varied both steering ratio and assist. BMW's Active Roll Stabilization was designed to counteract body lean. With the optional sport suspension, the 525i, 530i, and 545i added Active Roll Stabilization, run-flat tires, and Active Steering. Options included DVD entertainment, a navigation system, front and rear park assist, heated front and rear seats, and adaptive cruise control designed to maintain a set following distance. Later in the model year came an optional head-up instrument display and satellite radio, plus, for all but the 545i, a Sequential Manual Transmission (SMT). Essentially a clutchless manual operated via a console lever or steering-wheel paddles, the sequential manual could also be set to shift like an automatic.