This issue has persisted since Forza Motorsport 2 which was the Cobra’s first appearance in the franchise. Like many cars which were modelled prior to laser scanning, the Cobra’s car model is simply inaccurate and outdated by today’s standards.
(Although the comparison gifs were taken in Forza Horizon 5, the car model is the same as in Forza Motorsport)
The front has a couple of issues. The vents are the wrong shape, the two outer vents are too wide, the small vent on the bottom is too small and narrow and the large center vent has a different curvature. The turn signals sit too low in proportion to the headlights and slightly too far out. The shape of the fenders is off and the bonnet is too large.
Onto the back, the tail lights are too tall, as with the front, the shape of the fenders are off here as well. The panel gap between the boot and the body isn’t quite right and the fuel cap sits too low and slightly to the right.
Onto the side, the hood scoop sits too far forward, the shape of the vent is off, the 427 badge is in a different position, the curvature of the wheel arches is off, the glass of the headlights and front turn signals is too flat and the front is too long. The wheels are also inaccurate with the center piece being too small.
Lastly, the stripes are too narrow and sit too apart. They should exceed the width of the hood scoop and the gap between them should intersect with the Cobra badge.
In closing, the Cobra is an iconic American sports car in dire need of a remodel as with many early car model which originate from Motorsport 1 and 2.