For cruising the streets, just to record any "incidents", hooligans, DWI, etc. , a Go Pro camera is desired.

Which ones can be set to 4 frames per second, with reasonable screen resolution?

Has the low-priced model been discontinued?

A real simple but effective camera mount, can be rotated for over the shoulder shots, sideways, or straight ahead:

Camera Mount by AviationMetalSmith, on Flickr