2006 BMW Roadster 3.0i

2006 was the year for Z4 upgrades, with new technology and engine offerings available in the roadster.

One of those new engines for the roadster was the N52 model inline six that usually powers 3 Series sedans. Displacing 3.0 liters, BMW built it with a magnesium-and-aluminum hybrid block casting to keep the weight down. Innovating further, they added their Vanos/Valvetronic variable valve system, which varies lift and timing to such a degree that the engine’s breathing is actually controlled by the valves and not the throttles. This technology not only produces more power, but actually improves gas mileage. The 3.0-liter six produces 215 hp with 185 lb-ft of torque at 2,750 rpm on the way to a melodious 7,000 rpm redline. A six-speed manual is standard with a six-speed Steptronic and, for a limited time, a SMG automated manual transmission as options. The EPA rates the 3.0i at an amazing 20/30 mpg (manual) and 21/29 (automatic).

But sports cars exist for the twisties, and the Z4 loves them. The Z4's suspension is an evolution of the M3’s underpinnings, with a strut-type front suspension and a mulilink setup in the rear. BMW engineers claim the Z4 roadster is 100 percent more structurally rigid than its Z3 predecessor. Reviewers have noted an absence of the dreaded roadster “cowl shake.” Motor Trend measured 0.94 g on their skidpad for a 3.0si roadster. But they were not happy with the slight disconnect between road and driver they felt. They suspect it was due to the Z4’s new electronically assisted steering, which they claim doesn’t subjectively equal the old-fashioned hydraulic type. Other reviewers found that the Z4’s array of Dynamic Stability and Dynamic Traction Control systems in combination with its 50/50 front/rear weight distribution allowed them to dial in the perfect combination of control for “spirited” driving.

Getting into the low-slung Roadster's cockpit is not for awkward people, but once inside BMW “solidity and style” surround you. The style, however, is that of a dedicated sports car, not a luxury grand touring machine. The dash layout is simple, and all the controls are at your fingertips. Wood and real brushed aluminum are also there, but the focus is on the road. A tilt/telescoping steering wheel is standard. The 6-way manually adjustable seats are contoured for spirited driving and can be upgraded to tighter-fitting M Sports seats. A manually operated convertible top with a heated rear glass window is standard, with an optional automatic top that takes 7 seconds to drop. Further, the convertible top retains a usable 8.5-cubic-foot trunk as it becomes its own tonneau cover when folded.

The Z4 earned four out of five stars in NHTSA frontal-impact crash tests. Every model is equipped with BMW’s standard array of safety features, including front airbags, active knee protection for driver and passenger, rollover protection with rollbars and a reinforced windshield frame, adaptive brake lights, and BMW’s full range of electronic brake system wizardry.