Secret City of the Automotive World: GM’s Milford Proving Ground Offers Free Fuel, Plate-less Rides
MILFORD, MICHIGAN - For over a century, hidden within the heart of Michigan, lies a fully-functioning, 4,000-acre city unlike any other. Milford Proving Ground, owned and operated by General Motors, is a sprawling vehicle testing facility where gasoline flows freely and prototype cars navigate roads without license plates.This unique environment, shrouded in secrecy, has been pivotal in the progress of GM brands for generations and continues to shape the future of automotive engineering.
The existence of Milford, purchased by GM in 1923 for just over $100,000, is largely unknown to the public, contributing to its mystique.But the facility isn’t simply about concealment; it’s a self-contained ecosystem designed to push the boundaries of automotive innovation. The free fuel and lack of registration requirements aren’t perks, but necessities within a closed-loop testing environment where vehicles are constantly evolving – and often, not yet road-legal. This allows engineers to focus solely on performance and refinement, free from the constraints of public roads.
Originally nicknamed ”The Rocks” due to its rugged, 267-foot elevation changes, Milford has grown to encompass over 150 buildings and a remarkable 150 miles of roads – 131 miles of asphalt and 16 miles of gravel. A continuous drive around the entire perimeter would take approximately two hours.
Strategically positioned between GM’s key centers in Flint, Detroit, Lansing, and Pontiac, Milford serves as a central hub for testing across various brands. The facility’s origins stem from a desire to shield prototype vehicles from public view, but it has evolved into a comprehensive research and development landscape. A key benefit for those working at the range is the on-site gas station, offering fuel at no cost. Furthermore, because all land is private and many vehicles are pre-production, traditional license plates are deemed unnecessary.
