Chevrolet set out to build 50 lightweight, aluminum-bodied 1962 Impalas purely to dominate the NHRA drag strip, but a body-panel stamping problem cut the run to just 16 or 18 actual cars. The result, badge-coded Z-11, is one of the rarest regular-production Chevrolets ever built, backed by a Winternationals-winning pedigree. Read on to find out why this 409-powered homologation special never even offered an automatic transmission.