It was in the news five years ago when the Dallas police (in the US) used C4 to blow up a suspect in a parking garage. It seemed to startle people then, mainly because they repurposed a normally bomb-defusing robot to do it.

In fairness, while it was in a garage, it was not on a car.

"We saw no other option but to use our bomb robot and place a device on its extension for it to detonate where the suspect was," Dallas Police Chief David Brown told a news conference Friday. "Other options would have exposed our officers to grave danger. The suspect is deceased as a result of detonating the bomb."

https://www.npr.org/sections/thetwo-way/2016/07/08/485262777...

Not if you have actually seen the device and it looks like a goddamn pipe bomb, as at least some of these tracking devices do. But if your response is anything other than running, I think you belong in a psychiatric hospital. Normal people run like hell when they think they've found a bomb.