Motorcycle Police?

They're not required for any missions nor do they unlock any missions.

They many have two advantages:

They don't generate transport request (so they are good for alliance missions where you have only send that one unit)

And of course they add the unit for players attempting to re-build stations realistically.

They effectively are just a realism option for patrol car variation.

There are very few real world scenarios where a motorcycle unit is required over an actual patrol car (although I do know of a department that made all their traffic accident investigators also be motorcycle based)

also a good unit to send to either shared alliance missions- or the timed missions -

I normally send them on calls that require three or more patrols but have only one prisoner to transport that way I don’t have all cars tied up and I only have the amount needed for transport or two cars as in case cars, my department isn’t set up on realism as that would make the game for me not as fun. Pointless probably for most but helpful for me personally.