I just found this sight that has a very cool idea for where to put a dry cell on a car.
They have made cells the size of a license plate so the can be mounted to the bumper behind the license plate.
I am not sure about their using metal for the end plates, and I don't think that they are using enough plates, but it is still a cool idea.
Here's their web site: http://evolutionhho.com/
Check them out.