A six-speed manual transmission is standard on all models, and a six-speed automatic is optional on all but the M for $1275. With the manual transmission, the 3.0i and 3.0si are rated at 20 mpg city and 29 highway; with the automatic they get 21/30. The M model has an EPA fuel economy rating of 16/24 and is subject to a $1000 Gas-Guzzler tax. All Z4s use premium-grade fuel.

The 3.0i roadster ($36,400) comes standard with a manual top with heated glass rear window, vinyl upholstery, air conditioning, interior air filter, tilt/telescoping steering wheel, cruise control, six-way manually adjustable bucket seats, heated power mirrors, power windows, power locks, remote keyless entry, AM/FM/CD player, iPod connectivity, outside temperature indicator, rear defogger, rain-sensing variable intermittent wipers, automatic headlights, fog lights, theft-deterrent system, 224/45R17 run-flat tires on alloy wheels.

The 3.0si coupe ($40,400) and roadster ($42,400) add leather upholstery, automatic climate control, center console, aluminum interior trim, THX audio system, trip computer, and map lights.

M Coupe ($50,100) and M Roadster ($52,100) get 225/45R18 front tires and 255/45R18 rear tires, a sport suspension, and xenon headlights with washers. Roadsters add a power top. Cruise control and the THX audio system are deleted.

A Premium package ($3,200) for the 3.0i includes a fully automatic top, automatic climate control, Bluetooth wireless cell phone link, eight-way power driver's seat with memory, auto-dimming rearview and outside mirrors, trip computer, BMW Assist, and interior storage nets. Leather upholstery ($1150) is also available. A Sport package available for 3.0i ($1000), 3.0si coupe ($1300) and 3.0si roadster ($1200) models includes sport suspension and BMW's Dynamic Driving Control, which has a Sport button that, when pressed, quickens throttle response, reduces power steering assist, and adds sport programming to the available automatic transmission. It also includes 225/45R17 front and 245/40R17 rear run-flat tires for 3.0i models and 225/40R18 front and 255/35R18 rear tires for 3.0si models.

Stand-alone options include the eight-way power seats ($995), M sport seats ($500), heated seats ($500), power convertible top ($750), fog lights ($260), xenon headlights ($700), navigation system ($1,800), BMW Assist ($750), and the THX sound system ($875).

Safety features include dual front airbags, front side-impact airbags, front knee airbags, LATCH-style child safety seat anchors on the passenger seat, ABS, brake fade compensation, brake standby, brake drying, EBD, traction control, antiskid control, tire-pressure monitor, and a hill-holder feature that prevents the car from rolling backward at a stop. Roadsters have two rollbars mounted behind the seats.