Greets,
Tomorrow, there will be an Accessible Transportation Fair surrounding Metro headquarters; methinks it'll be for most of the day. I think just about everyone will be sending a vehicle, and since it's a celebration, they're probably sending their best vehicles...so if you want to see a rainbow of transit systems all in one place, head on down to Gallery Place.
I'd go, but my boss will be there.... ;)
Also, the day after that (Wed), I will be attending the ECOmmuting Fair at Nat Geo hdqtrs, 17th & I NW. I know we're not sending a vehicle, but others might. There will also probably be other types of interesting commuting vehicles as well.