Old VWs are very popular for electric conversions.
Right now, I am thinking about doing a 72 volt system. I took a good look at
Dr. Larry's Electric Metro page, and it's a pretty nice setup.
His can get up to 70 mph on a fresh charge. I am keeping the manual 5-speed transmission and expect to be able to go 45 mph easily.
Range is going to be less. I am shooting for 30 miles. Lead-acid batteries just don't hold a lot of energy for their size and weight. You can convert a car that would go 50 mph and go 60 miles, but you would need a LOT of batteries. And it's diminishing returns. The more batteries you have, the more weight you are lugging around.
It seems to make more sense to design around more modest speeds and ranges, then carpool or take a fuel efficient gas car for long trips.