Hey Doctor Bob,
If I was building another electric Geo Metro, I WOULD start with a 4-cylinder model, as it does have the the transmission over farther, which gives you a little more room.
It wasn't a big deal using the 3-cylinder model, but it did just happen that I had the exact biggest motor that I could possibly fit in there, both in terms of length AND diameter.
I think it was a good choice for a motor and has been working very well for me. More and more, the car is becoming less experimental. It just plain works. I drive it and find myself thinking about design issues less and less.
The series-wound motor works great. A shunt-would (or compound wound) would be pretty neat in that you could use regenerative braking. Of course you would need a different controller, and it's a bit more complexity, be it would be cool!
