The REx hold up for about 60-65mph on flat ground without climate control. Change those parameters and you’ll still eat battery, just less of it. In the NA config of the car where the REx only comes on at 7% battery, this is a critical failing, but OBD coding the car to enable on-demand REx at any point below 75% (and then hold state of charge) transforms it into a whole new beast that’s extremely road trip capable.