General Motors, who had taken over the impetus in developing a reliable and durable crash test dummy, found neither the VIP-50 nor Sierra Stan satisfied its needs. In 1971, GM engineers decided to combine the best features of the VIP series and Sierra Stan by combining Sierra Stan's head with VIP-50's body. Hybrid I was born. Hybrid I was what is known as a "50th percentile male" dummy. That is to say, it modeled an average male in height, mass, and proportion. The original "Sierra Sam" was a 95th percentile male dummy; heavier and taller than 95% of human males.