For his day job at Mazda's North American r&d center in Orange County, Coleman leads a 20-member team comprising mainly Japanese engineers on assignment, with about a half-dozen permanent American employees.
Its first job in vehicle development is to make sure basic specifications are suitable for American drivers.
Later, his team refines the feel of U.S.-spec cars by testing them on American roads. Japanese drivers tend to want their steering to feel light and easy, Coleman says, but Americans want a firmer feel. Americans also need a more forgiving suspension because U.S. roads are much rougher than those in Japan.
"We've got really skilled guys in Japan who are making everything happen," but it's useful to have an outside team of U.S. engineers guiding their work, Coleman says. "It's important to keep our calibrated butts out of the process."
Mazda's priority for the MX-5 was to make it friendly to everyone from novices to experts. Instead of tuning it to stay flat through corners, Mazda tuned the steering and suspension to roll in a controlled manner, intuitively communicating the car's limits.
Engineers tuned the suspension to be cushy.
A stiff suspension is enjoyable on the track and on well-maintained roads, but it can be punishing in real-world conditions.
"I like to say, 'The good roads are always bad roads,'" Coleman says. "Our suspensions have to be soft enough to handle well on a bumpy back road, because those are the roads where you're actually going to have fun."