During World War II, the Willow Run site in Ypsilanti Township built one B-24 bomber plane an hour at peak production. That same industrial footprint is still going strong, but instead of planes, it’s testing the vehicles of tomorrow. What happened between those two chapters is, in many ways, the story of Southeast Michigan itself.
General Motors shuttered its manufacturing site that once employed thousands of workers in 2009, causing employment in the area to drop sharply. The site was contaminated, the community was shaken, and the question hanging over the property was a familiar one in the post-industrial Midwest: what do you do with land like this?
The answer was to build something Michigan had never seen before.
The American Center for Mobility (ACM) now occupies the former Willow Run industrial site, born from a coalition of regional economic developers, state and local government leaders, university researchers, and industry partners who decided the property deserved something more than remediation and resale.
Ann Arbor SPARK was part of that coalition from day one. SPARK CEO Paul Krutko was involved in the earliest conversations about what a brownfield site of that scale could become. The timing wasn't coincidental. Autonomous and connected vehicles were beginning to capture serious industry attention, and Michigan needed infrastructure to match its ambition. The University of Michigan had opened M City, a smaller research track, but the industry needed something larger: a proving ground where companies could test and validate vehicles before they went to market.
ACM opened in 2017 as exactly that. The brownfield site, with its existing road network, turned out to be an asset rather than a liability. Michigan's Department of Transportation even incorporated real highways into the test track. Some of those signs are still up.
ACM’s President and CEO, Reuben Sarkar, says ACM functions as "a global development center" — a shared infrastructure resource where companies co-locate and focus on product development rather than rebuilding costly foundations from scratch. "If every company out there tried to rebuild all this, it's just a lot of wasted money," he says. "We'd rather have them share the infrastructure and the expense and focus on their product development."
The infrastructure includes a full test track, high-power EV charging, secure co-location space, and a 90-megawatt substation. Building something equivalent from a green-field site could cost hundreds of millions of dollars. At ACM, companies share it.
What gets tested there has expanded well beyond connected and autonomous vehicles. EV charging infrastructure, cybersecurity systems, autonomous ground vehicles, and robotics companies have all found uses for the facility. Several of those uses weren't anticipated until a company showed up with a need ACM hadn't considered before — a startup testing inspection robots in the facility's water mains, an autonomous grounds crew that now cuts ACM's lawn in exchange for testing access. The facility's approach is less about a fixed menu of services and more about problem-solving with whatever a company brings through the door.
ACM's partners span traditional OEMs, tier-one and tier-two suppliers, consulting firms, national laboratories, academic institutions, federal agencies, and startups at various stages of growth. Large companies typically arrive with a defined product development cycle and a testing schedule tied to federal compliance requirements. Smaller companies access the facility differently.
Michigan offers grant programs specifically designed to fund testing at state-designated facilities, and ACM works directly with eligible companies to help them access that funding. Garages and track time can be shared. The facility has also used barter arrangements, exchanging track time for equipment or data when it serves both parties. "There is a model that fits almost everybody here," Reuben says.
One of the less visible things ACM does is keep work in Michigan that might otherwise happen somewhere else. As vehicles become more software-defined, the testing required to bring them to market has become more specialized. Companies that can do that work in Michigan tend to deepen their roots in the state. Reuben describes a pattern he has watched on repeat: a company comes in for a tour, doesn't think they have a need, and then starts connecting dots. Another arrives to test, and ends up expanding its on-site presence significantly. One company relocated to Michigan independently and then began broadening its footprint at ACM. Several startups are now growing out of the property itself.
"People will invest where they can test," Reuben says. "And if a facility like this wasn't here, that work might happen in another state."
The economic impact is still being tallied. Close to 100 people now use ACM as a worksite, between staff and resident tenants, and roughly 50,000 people have come through the facility's gates over the past five years. A fuller economic impact accounting is in progress and expected this spring, and those figures will tell a more complete story of what the facility has generated for the region since opening.
SPARK's involvement didn't end at the groundbreaking — the two organizations share leadership and a vision. SPARK's CFO serves as ACM's CFO, functioning as an extension of ACM's operations team. Paul Krutko sits on ACM's board as treasurer. SPARK connects ACM to its broader network of regional stakeholders, prospective customers, and companies new to the area — a relationship that has remained operational, not just ceremonial, since the facility's founding.
The ongoing partnership reflects something larger about how Southeast Michigan has built its mobility identity. Detroit brings a century of automotive manufacturing. Ann Arbor brings research, tech, and talent. ACM sits at the intersection of both. And SPARK's continued seat at the table is part of what keeps those two worlds connected. The companies using ACM's facilities include every major OEM alongside the software and automation firms redefining what those OEMs build. That combination matters at a moment when the industry is changing faster than it has in decades.
After a period where autonomous vehicle timelines were reset industry-wide, demand for what ACM does is accelerating again. ACM posted its best commercial sales year on record in 2025 and is tracking ahead of that pace in 2026. The work coming in isn't speculative research. "When people are validating things, we know that they are getting ready to go to market," Reuben says. "That's our measure — what are people validating? When they're validating something, it usually means they're getting ready to launch new products."
For Southeast Michigan, that readiness is the signal worth watching — and SPARK helped build the infrastructure to receive it.