Widmann said the move won't fundamentally change the car.
"The general layout of rwd has morphed over time, but it's still the general architecture that it has been," he said. "In the architecture world of a rwd — which you're going to end up with a rwd architecture — I think these pieces of it are pieces that will always work. As you tune it and put a top hat on it, you can get different combinations and can define a lot of the emotion."
The current-generation Mustang resonates so well, Widmann said, because of its styling, diverse powertrains and driveability on or off a racetrack.
The team worked to give the 2015 model a more aggressive look while keeping traditional design elements. The vehicle's footprint was unchanged, but the roof and hood were lowered about 1.2 inches. Visibility also was key, Widmann said, as the team tried to maintain the previous generation's proportions.
"It's critical to always have the ability to keep theme elements but not be stuck in a rut," Widmann said. "It's a balance of not being caught in the past but still moving forward, which is a tremendous trick."
Ford has made incremental improvements since the 2015 redesign, adding a 10-speed automatic transmission and dropping the V-6 engine in 2018. It also has reintroduced special editions, including the Bullitt and California Special, and revived performance variants such as the Shelby GT350 and Cobra Jet.
Although U.S. sales are down 4.8 percent this year to 48,362 through July, the car is outselling its chief rivals: the Challenger and Chevrolet Camaro.
"It's the heart and soul of Ford," Jim Farley, Ford's president of global markets, said at a celebration this month of the 10 millionth Mustang produced. "It's one of the reasons why we're different and it continues to inspire other vehicles in the lineup."
