> I really hope people don't start doing this on their own.
People have been doing electro conversions of regular cars for many years. Popular conversions are Porsche 914, the Beetle and the Toyota MR2. There are companies that sell kits for many of these and others besides.
Most of them are quality wise a notch (or two) above what is shown in the article, but typically do not have as much range because of the more practical nature of their design. If you're willing to give up all the usable space in the car for batteries then probably you can get any one of those to that same range or even more.
http://germancarsforsaleblog.com/1975-porsche-914-electric-v...