The Institute credited "a modified front-end structure and a new optional automatic-braking system" for improvements in the Fusion's performance.
"The beefed-up front end improved the Fusion's performance in the small overlap front test from acceptable to good," the Institute said in a statement on Tuesday.
The test is designed to replicate what happens when the front corner of a vehicle collides with another vehicle or an object like a tree or utility pole.
The 2017 Fusion earned "good" ratings in the Institute's other crash tests.
Standard safety equipment on the 2017 Fusion includes electronic stability control, antilock brakes, a rearview camera and eight airbags, including driver and front passenger knee airbags.
Optional safety equipment includes rear inflatable seatbelts, pre-collision assist with pedestrian detection, a blind-spot information system, lane-keeping assist and adaptive cruise control with forward-collision warning.
The National Highway Traffic Safety Administration has not rated the 2017 Fusion.
Edmunds says: Car shoppers keeping score should note that the Insurance Institute for Highway Safety has not rated the 2017 Honda Accord, Kia Optima, Mazda 6 or Toyota Camry.