> It’s likely the first non-Tesla vehicle to run FSD, and it achieves 258 Wh/mi — roughly matching the efficiency of an actual Model 3.

This claim is implausible, right? The Mustang is unambiguously less aerodynamic than the Model 3; there's no way it is achieving similar efficiency, especially at highway speeds.

The Mustang is from before modern safety laws (and feature expectations) and therefore weighed a lot less than your average modern car.

A stock '66 Mustang hardtop had a curb weight below 3000lb, in the lightest configuration close to 2500lb.

Less mass to move will do a lot for efficiency just like aerodynamics will.

Of course, you will also die or be horrifically maimed in an accident in a 1966 Mustang that you might walk away without any serious injuries from in a modern vehicle.

Yes it is implausible. But I imagine that they are probably not running it at 70 mph everywhere, just pootling about in suburbia