1983 Porsche 956 Group C 25 June 2021 1983 Porsche 956 Group C, chassis no. 956 Not sold. Highest bid $2,900,000 estimate of $4,500,000 – $6,000,000 Auction: RM Sotheby’s Monterey 2021 Matthew Howell © 2018 Courtesy of RM Sotheby’s