“What does a doctor drive?” That’s a common question. “What does a doctor’s dog drive?” isn’t. But it’s a question you might ask when meeting Dr. Billy.
The heart of a renaissance man
Words by Kyle Fountain
Photos by Dr. William Cohn
When Billy isn’t performing surgery, he can often be found at “Billy World,” officially named the Center for Device Innovation at the Texas Medical Center, but “Billy World” has a nice ring to it. The center is packed with all the tools Billy and his team need to push the boundaries of medical innovation, including top-of-the-line 3D printers capable of printing multiple materials simultaneously, computer-controlled milling machines that can work on several different types of materials, and anything else he could possibly use to advance the field of artificial heart technology.
But how did he come to be so driven to innovate? The answer costs about a dollar and fits in your pocket: a humble Hot Wheels car. When Billy was a child, the introduction of Hot Wheels changed the course of his life. He wistfully and enthusiastically waxes poetic about how easily they rolled: “Hot Wheels came out with that super low friction and the way they would go down a track; kids had never experienced that kind of physics before.” Billy and his brother were enamored, but while his brother moved on to rockets and other passions, cars remained one of Billy’s greatest loves.
That fascination with cars and love of all things automotive manifested itself in a number of excentric vehicles, one of the first examples being a 1960 Triumph TR3. After he blew the stock engine, Billy built custom motor mounts and installed a Ford 2300 engine and a five-speed transmission. He later modified two 1998 Toyota Supras with gigantic HKS turbos to put out over 800 horsepower, and continued wrenching on a German luxury sedan built to cover large swathes of the Autobahn and a monolithic SUV with tinted windows. But one of, if not his most fascinating car, was a fully remote-controlled 2004 BMW 330i convertible.
Fast forward to 2025, and after years of being asked why he hadn’t ever made an art car—due to his automotive and building passion—Billy finally took the plunge. His entire family got involved by brainstorming countless possibilities, from a car with a snail shell to a gigantic inchworm. After a myriad of ideas and some debate, they settled on a life-sized remote-controlled car. Billy’s mechanical and tinkering brilliance was on full display as he brought his family’s concept to life with high-torque, low-RPM brushless electric motors to turn the wheel, and linear solenoids to operate the throttle and brakes. The cherry on top was training the family dog, a four-year-old English Sheepdog named Andy, to sit in the driver’s seat for the parade. Of the crowd’s reaction to seeing a dog behind the wheel, Billy simply says, “They went absolutely ape sh*t.”
Surprisingly, the remote-controlled BMW, complete with an English Sheepdog in the driver's seat, somehow isn't Billy’s most infamous car. That honor goes to his McLaren 720S. If you happen to follow Houston-based car spotter groups, there's a good chance you’ve seen his McLaren with its now-iconic Hot Wheels wrap. Despite Billy’s lifelong love of Hot Wheels, the wrap was actually the result of his friendship with Hot Wheels design director Brian Benedict, which was also coincidentally related to the Art Car Parade.
In 2022, before Andy made his parade debut, Billy was invited to be a judge at the parade, as was Brian, and Billy and Brian struck up an immediate friendship. A few months after the parade, Brian reached out with a monumental ask of his new friend: he wanted to know if he could borrow Billy’s McLaren, have a custom wrap put on, and exhibit the car at an event. While Billy was initially apprehensive about having his near-daily driver made to look like a life-sized Hot Wheels car, he was happy to oblige when Brian informed him that he wanted to display the car at Trae Day, which Hot Wheels was sponsoring. Trae Day is a weekend-long block party in collaboration with Houston rap legend and activist Trae the Truth. The block party was originally created to commemorate Trae’s philanthropic work for the community during Hurricane Harvey.
In preparation for the spotlight, Billy’s Azores Orange McLaren received a bright orange livery complete with racing numbers and the iconic flaming Hot Wheels logo. It was so striking, and the car was such a massive hit with families, that Billy decided to keep it.
When talking about his history of interesting vehicles, Billy makes a point of stressing that he isn’t a collector, preferring to drive his cars and work on them himself. He is also more than happy to share the excitement of his cars—by letting them snap a photo or giving an enamored child permission to sit in the driver’s seat—with others, knowing that something as simple as letting a child sit in his McLaren could ignite the same life-long passion that Hot Wheels did for him all those years ago.
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