We have dedicated jail wagons, for which I am grateful.
That said, we do have to transport our own DUI suspects for blood draws. They must sit in the rear, handcuffed behind the back, and a second unit must follow. I was following a buddy who was transporting a female DUI suspect. She kicked my buddy in the shoulder causing him to nearly swerve into the center concrete divider. I saw his car jerk and then the flash/confetti of a Taser deployment. She rode the rest of the way with probes in place.