Modern simulation tools and digital design aids allow carmakers to sculpt exteriors without building prototypes or carving clay models for wind-tunnel evaluation. There are applications for creating and developing engines, transmissions, and chassis components. But when it comes to the fine art of designing interiors, the tool of choice is the 50-year-old contrivance shown here called an H-Point Machine (HPM).
The fundamental data point revealed by this human surrogate is the precise location of a seated occupant?s hip joint, hence the name. Why does that matter"  Because humans touch more parts of the car than would a rabid octopus. The design process thus begins at the H-point with the noble aim of comfortably accommodating occupants, but it quickly encompasses roof height, door openings, passenger restraints, airbag operation, collision performance, outward visibility, and driver fatigue. The list goes on. The HPM consists of two molded-plastic pans that mimic the back sides of a human?s thighs, buttocks, and torso. True to life, these components hinge about the H-point, which is precisely indicated by crosshairs. Steel components serve the skeletal role, providing a means of connecting lower leg, ankle, and foot proxies and placing weights at appropriate locations. Bubble levels and protractor scales facilitate installation and measurement tasks.  The HPM is designed to compress the seat cushion and backrest exactly like a human; the beauty of this tool is tha...