1930 Alfa Romeo 6C 1750 Gran Sport Spider 21 April 2016 1930 Alfa Romeo 6C 1750 Gran Sport Spider Sale: RM Sotheby’s Monaco classic car auction on 14 May 2016. Estimate: €900.000 – €1.200.000 NOT SOLD Photo Credit: Tom Wood ©2016 Courtesy of RM Sotheby’s