It is a BMW i3 by the look of things - it should in theory be able to go as fast in reverse as forwards being an electric vehicle.
We've got a BMW hybrid - it has around 87bhp from the electric and another 180bhp from the petrol engine - it is pretty nippy just on the electric. I can't remember if it goes through the autobox on the electric but if it did then you'd be limited to the maximum speed of the electric motor in reverse. I'm pretty sure it is a direct(ish) drive though so the reverse in electic *could* give you the same speed as it does in drive. I would suspect that BMW have restricted the maximum speed in reverse though electronically.In theory? In theory, a car with an internal combustion engin should be able to go as fas in reverse as forward as well. What slows it down? The same thing that slows electric vehicles - gearing for an ICE, or throttle sensitivity on an EV because people don't want to try to hold the pedal at 1/130th of a pedal press to go 1 mph in reverse.