@Invictus going from 30 to 50 mph is more important and practical than going 120. if you design the engine to not be powerful enough to surpass 60, youre making it harder for drivers to make evasive maneuvers or reach safe highway speed. highway onramps are designed with this in mind, so by doing this youre requiring every highway to redesign themselves, taking up MORE room and many millions of dollars.

you are also wrong that crash protection isnt important below 55, its common to see uglier accidents at low speeds than on highways.

this isnt an unpopular opinion this is a poorly established hypothesis presented as authoritarian oppression