Unlike earlier prototypes that have been spotted on the streets of Detroit, the new performance version of the Fusion is equipped with a sportier alloy wheel design that hides enlarged disc brakes.
Perhaps the biggest giveaway are the set of four exhaust tips hanging out the back. Partially covered by the car's disguise shroud is a lower air intake with a large radiator behind it.
Elsewhere, this car features updated headlights with a thin set of LED driving lights marking out its lower edge and new tail-lights that incorporate a chrome spear.
Under the bonnet, rumours are that the Fusion ST will be powered by a version of the 2.7-litre twin-turbocharged V6 that's used in the F-150 pickup truck. It's said that the ST's motor will have around 240kW of power, and will be tied to a six-speed automatic transmission and all-wheel drive.
The new Fusion ST is expected to go on sale in the US during the first half of 2016, and may possibly debut along with the rest of the revised Fusion lineup.
It's not known at this stage whether the Fusion ST's drivetrain will be installed in its Euro-focussed Mondeo hatch and wagon siblings.
Indeed, it's not clear, given that the latest-generation Mondeo was launched in Australia in April, when the Fusion's facelift will be applied to the Mondeo.