Sometimes those electrical maintenance vehicles carry
rubber tire chocks/wedges on the outside of the vehicle.
I ran over one of these once at 40 mph and it really banged up the undercarriage. At 60+ mph, it could easily bounce a car up like that.

I work at a warehouse with a truck yard and a driver recently almost drove off with one of those balanced on the rear "bumper" where is most certainly would have fallen in the road somewhere. It's not actually bumper because a real bumper would be so high that other vehicles could pass right under it, so it's a metal frame structure with a horizontal bar of rectangular metal that hangs down behind the wheels and provides enough surface area to set a few things down. I set my clipboard on them somewhat frequently and I guess I'm not the only one who sets stuff there when working the doors and such.
I don't know if it was one of our wheel chocks because we anchor ours to the ground with chains by the docks, but it just goes to show how quickly and easily things can go horribly wrong and how little control you have over it.
The truck picked up an empty trailer at the back of the facility and drove all the way around without it falling off. That's at least 1/2 a mile so it isn't a stretch to think that it would have made it another mile or so to the 70MPH Interstate highway. Hell, the surface roads here are 55MPH so it still could have been tragic even if it didn't get that far.
Scary.