We built this car to enter a series of national races here in the Uk - Details can be found at http://www.greenpower.co.uk.
To some degree this controlled how we built our car and what we used as the race series has rules that must be followed.
The chassis was a simple "Ladder" design made from 19mm aluminium square section tubing. This is easy to work and light as well as moderately low cost.
The various sections were joined with aluminium plates and pop rivets. We followed a Greenpower design as the basis for our car but made numerous changes along the way.