The only thing more fun than a convertible is a BMW convertible. But the 2007 BMW Z4 is more than just a roadster; it's also available as a coupe. Either way, the Z4 is one of the more entertaining cars you'll likely experience.

The Z4 is one of BMW's newer models. Introduced in model-year 2003, it was originally available only as a roadster, with the coupe joining the lineup just last year. The roadster has lines that can be somewhat polarizing, but the coupe -- compact and sinewy -- has the sort of looks that most are likely to appreciate. What both vehicles share, though, are outstanding driving dynamics, though the coupe will likely be the Z4 of choice for most enthusiasts. The fixed roof of the 2007 BMW Z4 coupe allows the car to enjoy a greater degree of body rigidity than its drop-top sibling, resulting in a stiffer, more performance-oriented ride.

With a price that starts in the mid-$30s, the BMW Z4 offers remarkable value in the luxury-brand segment. The Porsche Boxster/Cayman and Mercedes-Benz SLK-Class offer similar driving dynamics and an equal measure of prestige, but cost thousands more. If you're looking for a convertible or coupe that delivers outstanding performance and the glamour of a high-end nameplate at a reasonably affordable price, the 2007 BMW Z4 is the only candidate to consider.

The 2007 BMW Z4 is available as a two-seat roadster or coupe. The roadster has a traditional, manually operated convertible soft top with a defroster-equipped glass rear window. Two trim levels, 3.0i and 3.0si, are available. The 3.0i (roadster only) comes with 17-inch alloy wheels, rain-sensing wipers with heated wiper jets, a tire-pressure monitoring system, heated outside mirrors, full power accessories, manually operated six-way adjustable seats, vinyl upholstery, a tilt-telescoping steering wheel and a 10-speaker audio system with a CD player. The 3.0si version adds leather upholstery, a center armrest, aluminum interior trim, a premium audio system, a trip computer and automatic climate control. Most of these features are available on the 3.0i as options.

An optional Premium package includes a one-touch power operation feature for the convertible's top, auto-dimming mirrors, power seats, memory for the driver seat and Bluetooth connectivity. Other options for the BMW Z4 include sport seats, upgraded leather upholstery, a navigation system and a Sport package that includes upgraded wheels and tires, a sport-tuned suspension and BMW's Dynamic Driving Control feature that quickens throttle response and reduces power-steering assist.

Two engines are available for the rear-drive Z4. The 3.0i has a 3.0-liter inline six-cylinder engine capable of 215 horsepower and 185 pound-feet of torque. The 3.0si has a high-output version that's good for 255 hp and 220 lb-ft of torque. Each trim comes standard with a six-speed manual transmission. A six-speed automatic with BMW's Steptronic sequential shift control is available as an option. According to BMW, a manual-equipped 3.0si can achieve 60 mph in 5.6 seconds. For both engines, fuel economy rates 20 mpg city, 29 mpg highway with the manual gearbox and 21/30 with the automatic.

Every BMW Z4 model comes with antilock disc brakes, a tire-pressure monitoring system, run-flat tires and a sophisticated stability control system. Passive safety features include rollover protection, side airbags, active knee protection and child-seat anchor points for the passenger seat. In NHTSA crash tests, the BMW Z4 roadster earned four (out of five) stars for its performance in frontal-impact occupant protection. It received a three-star rating for side-impact safety.

In nearly all performance aspects, the 2007 BMW Z4 shines. Acceleration, braking and handling are all excellent. The Z4 is in its element on lightly trafficked roads where one can push the car toward its limits and enjoy the engine's sonorous exhaust note. From an everyday driver standpoint, the Z4 is still mostly agreeable. Wind and road noise on the roadster can be bothersome at highway speeds, however, and some drivers might find the ride quality produced by the optional Sport package's suspension to be a bit too stiff.

Simplicity is the prevailing aesthetic within the 2007 BMW Z4's cabin. This is a driver's car, and as such, the cockpit's furnishings offer little to shift your focus from the road. The cabin offers a broad dash, pleasant gauges, firm sport seats and not much else. There's lots of standard metallic trim, though, and wood trim is available for those seeking a more opulent look.

Drop-top drivers won't have a problem navigating either the manual or power-operated convertible tops; both versions are intuitive and a snap to operate. And lowering the top doesn't result in compromises with regard to storage space in the truck. With the top down, the BMW Z4 roadster's 9-cubic-foot trunk capacity remains almost unchanged. For comparison, the Mercedes SLK offers 10 cubic feet of cargo space with its hardtop up but considerably less in top-down configuration.