The first engine in this family was introduced in 1961 for the 1962 model year Buick Special with Buick's engine, the first V6 in an American car (The GMC V6 was used earlier in trucks). Because it was derived from Buick's aluminum V8, it has a 90° bank between cylinders and an uneven firing pattern due to the crankshaft having only three crank pins set at 120° apart, with opposing cylinders (1-2, 3-4 and 5-6) sharing a crank pin in, as do many V8 engines. The uneven firing pattern was often perceived as roughness, leading a former American Motors executive to describe it as "Rougher than a cob."