Aero improvements went beyond wind tunnel testing to get the 2018 Ford Mustang down—literally. Ford is touting the aerodynamic improvements that came after vehicle dynamics engineer Mike Del Zio complained of nose lift in the facelifted model as he tested the car around the automaker's Romeo Proving Ground north of Detroit.

"We had changed the hood profile, expecting better vehicle dynamics," says aerodynamics engineer Jonathan Gesek. "We were going for a 'confident' feel."

Ford began work on the facelift by the time the 2015 Mustang went on sale in late 2014. The task was to maintain or improve the 2015-17 Ford Mustang's handling confidence while improving aerodynamics as part of a fuel efficiency increase to help the automaker reach corporate average fuel economy (CAFE) requirements. But after Del Zio tested the facelifted car with the new hood, Ford had to rework the lower fascia and front splitter to regain that "confident" feel. After Del Zio's initial drive, Gesek applied a piece of duct tape to the lower gap of the nose in order to reduce front-end lift.

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"That little strip of tape made all the difference," Del Zio says.

Better downforce doesn't automatically increase fuel efficiency, though the right combination of countervailing aero efforts can help assure that it doesn't reduce fuel economy gains made elsewhere. The 2018 Ford Mustang GT's optional automatic transmission is a new 10-speed unit, replacing a six-speed, and makes the largest fuel economy gain among iterations of the model, at 5.6-percent. City, highway and combined fuel economy each rise by 1 mpg, to 16/25/19.

The Mustang GT manual, still with six speeds, is unchanged at 15/25/18 mpg city/highway/combined.

The Mustang GT's 5.0-liter V-8 is rated 460 horsepower and 420 pound-feet for the '18 model, up 25 horses and 20 pound-feet over the '15-'17 models.

Ford says that active grille shutters standard among '18 Mustangs not equipped with the Performance Pack, reduce drag by completely closing off the grille, sending air over and around the car, instead of through it.

Also for 2018, the Ford Mustang's 2.3-liter turbo EcoBoost four gets a 30 pound-foot increase to 350 pound-feet of torque, though horsepower is unchanged at 310. The EcoBoost-powered Mustangs benefit from a 4.2-percent fuel efficiency increase, to 21/32/25 mpg (up 2 mpg in highway driving and 1 mpg combined) when equipped with the 10-speed automatic, and to 21/31/25 (up 1 mpg highway and 1 combined) when equipped with the six-speed manual.