the Dymaxion car No. 1 chassis was
made of “chrome-molybdenum” (an alloy of elements including
Chromium, Cr and Molybdenum, Mo) aircraft steel, which has
an excellent strength to weight ratio. Note the dished lightening
holes (which were added to keep the weight down). The photo
below shows Starling Burgess (in the driver’s seat) and “Bucky”
Fuller (far right), and others looking on, before the initial road test.

Starling Burgess looks to be wearing a fur coat and leather helmet.
There is no sign of seatbelts, or anyone to act as “navigator”.
The words in quotation marks and photo, above, are from;
The Dymaxion World of Buckminster Fuller by Robert W. Marks
published by Southern Illinois University Press in 1960.