[kach22i]

1982 Williams FW08B
Built but unraced Formula 1 cars - Forum - F1technical.net

The FW08B was a six-wheeled (4 driven wheels at the rear and 2 undriven wheels at the front) variant that originated from the FW07D (also six-wheeled). It never raced. Patrick Head specifically said that the reason it was banned was because "someone in a FOCA meeting said it would drive up costs and cause chaos during pitstops". The FIA promptly limited the number of wheels for all cars to four, of which only 2 may be driven.

http://www.f1technical.net/forum/viewtopic.php?f=12&t=15297