I initially was going to use a DC motor, but now I’m leaning towards AC. This website has a lot of great information on AC vs DC:

http://www.cameronsoftware.com/ev/EV_DriveType.html

Those are all good points, but I’ll add some more I found:

* Regenerative braking. I have quite a few hills by my house and I want this benefit.

* Better motor efficiency

The Warp 9 (what I was considering using) has this performance graph:

In general, never better than 80% efficient. Better efficiency is better range!

Consider the AC-50 motor from Thunderstruck Motors. It has up to 94% efficiency and it is in the higher RPM range (better for my transmission, which will produce higher RPMS).

Also, another great read about AC motors on the Metric Mind website.