Water wheel charger?

According to the technical specifications for the 94Ah i3 (See: https://www.press.bmwgroup.com/global/article/search/tag:136/category:11/attach-lang:2/) it can regenerate at a rate up to 50 kW! Instead of putting in a dinky 7.68 kW (240V 32A) "Level 2" charger you could put your car on a roller driven by a water wheel and get a 50 kW charge rate.

Of course, things will go wrong when the battery gets hot or gets close to full. The car will stop charging and will put all that energy into the brakes instead.

It should work! Clearly, no one knows what to say at this point, but if you build it, and take pictures, I am sure we will all cheer you!