Where can I find other vehicle avatars?

In theory, you could make your own, but it's an involved process.

http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=78125

Otherwise, there's no other place to get them. You or someone else would have to make the person.

Thanks for the link.

Not sure whether I'll try making my own though. 36 images of 3D perspective and another 36 of overhead view sounds like a lot of work!

I bet some clever person somewhere has made a few and uploaded them.