If you build it yourself then some /many of the regulations don’t apply. For example you don’t need airbags (in Massachusetts). It varies by state: https://www

If you build it yourself then some /many of the regulations don’t apply. For example you don’t need airbags (in Massachusetts). It varies by state: https://www.semasan.com/resources/everything-you-need-register-and-title-your-hobby-car-all-50-states https://www.semasan.com/resources/everything-you-need-regist... Roughly the same thing is true for airplanes - experimental (“home built”) have to be airworthy but not certificated. They say it’s due to long tradition of DIY vehicles in America.