[OldHand2018]

The actual requirement is a series of rear visibility tests that are done on a vehicle through the full range of seat adjustability.

A rear view camera allows any vehicle to meet the regulation regardless of vehicle styling and design. They are cheap, too.

But they are not strictly required. Your average 1980s sedan probably would meet the requirement as long as it had mirrors on the driver and passenger side.

Here is the regulation: https://www.law.cornell.edu/cfr/text/49/571.111

[throwaway0a5e]

You're not wrong but in practice they're all but required because the corner that fuel economy and cabin strength requirements box you into is a corner with really high belt-lines and really poor visibility. You couldn't build something that's the shape of a 1990s sedan today.