Spring RTS Engine

I was browsing Digg today, and found an interesting video that, in my opinion, should be watched by anyone planning to model a vehicle. Even if you already know how differential gear works, the video should prove to be an entertaining and insightful review.

It is at http://www.youtube.com/watch?v=K4JhruinbWc

this is absolutely, positively great. except for the digg part.