It sounds like the Germans are developing it for use solely on the AutoBahn - They have some elaborately equipped service stations every so many Kms in the center median. Years ago when so many folks drove VW Beetles, you could actually get a new windshield installed at some of those stations in 15 or 20 minutes. You don't exit the freeway to use those stations . . . . they're located in the median so they can be used by vehicles travelling both directions
I would guess that it will be set up for use with any EV, and require no modifications (other than a hitch) to the car. Hook it up, pull out onto the freeway, hit an R/C controlled switch and it will probably push the EV down the slow lane at a pre-set speed of 100 kmh or so and probably disengage automatically when you tap the brakes. Range is probably just enough to get you from one AutoBahn service station to the next one, where you'll swap it out for a freshly charged one - Almost like driving on a toll road . . . . one station to the next
Because of the carefully thought out spacing of their service stations in the median of the AutoBahn, I could see this working really well . . . . over there. We really don't have the infrastructure for it to be practical here
Don