Schroth ASM Autocontrol III safety harness - Alpina Roadster S Supercharged

The standard three-point seat belts were replaced with Schroth ASM Autocontroll III safety harnesses to complement the Recaro racing shells. The ASM Autocontrol III features an auto-locking inertia-reel that allows for free movement in normal circumstances and locks up during abnormal movement, keeping the driver in place. The inertia-reel is usually mounted to the C-pillar or the seatbelt mounting points in the back seat. Obviously the Z4 roadster doesn't have a back seat or a C-pillar. Instead we decided to mount the inertia-reel to the mounting points of the original seat belt tensioner. Z4 coupe owners also have the option of mounting a harness bar between the C-pillars. The lower mounting points for the seat belts were reinforced with underbody reinforcement plates.

In practice, the auto-locking feature of the inertia-reel didn't work due to the limited space behind the seats. Although you will lose some practicality, the secure and tight feel of the safety harness is a big improvement over the stock three-point seat belts. The stunning looks of the safety harness are complemented by leather shoulder pads featuring an embossed Schroth logo.