Please help me identify this odd-looking component

It's a piezoelectric disc buzzer with a weight. It's being used as a vibration sensor, not a sound generator.

The weight amplifies the strain produced by vibration.

My answer is an educated guess.

It looks like a vibrating plate that is activated when the vehicle is shaken or something like that. On the plate, in the centre, you find a piezoelectric element converting the mechanical movement into an electrical one. From there on it should be clear.