Those Germans engineer some interesting stuff.
The most exotic use for a Wankel engine (itself an exotic German-invented combustion engine) is the seat belt pre-tensioning system in the New Beetle and some Mercedes-Benz models. When the deceleration sensor in the car detects a potential crash, it triggers small explosive charges. The expanding gas from those charges is piped through tiny Wankel engines, which then rotate to take up the slack in the seatbelts.
This is why Germans keep losing wars--they go overboard with the engineering. The German design philosophy seems to be, "Why use three simple parts for the job, if you can use eighteen complicated ones?"