The US regs I've seen written for 'autocycles' will not allow for kitcars, three-wheelers, or other 'homebuilts', unless you add in safety features -
Ҥ 30114. Autocycles
“(a) Interim safety standards for autocycles.—During the period beginning on the date of the enactment of the Autocycle Safety Act and ending on the effective date of the rules issued pursuant to subsection (c), a person satisfies the requirements set forth in section 30112(a) with regard to an autocycle if the autocycle—
“(1) complies with the motor vehicle safety standards for passenger vehicles with gross vehicle weight ratings of less than 10,000 pounds, as set forth in Part 571 of title 49, Code of Federal Regulations, relating to—
“(A) seating systems (FMVSS 207);
“(B) belted occupant crash protection (FMVSS 208);
“(C) seat belt assemblies (FMVSS 209);
“(D) seat belt assembly anchorages (FMVSS 210);
“(E) child restraint systems (FMVSS 213);
“(F) roof crush resistance (FMVSS 216);
“(G) child restraint anchorage systems (FMVSS 225); and
“(H) flammability of interior materials (FMVSS 302);
“(2) meets the performance criteria relating to upper interior impact set forth in FMVSS 201 to the extent possible to reach the target points;
“(3) is equipped with a steering wheel air bag, 2 curtain side impact air bags, anti-lock brakes, and electronic stability control; and
“(4) complies with the motor vehicle safety standards for motorcycles, as set forth in Part 571 of title 49, Code of Federal Regulations, relating to—
“(A) brake hoses (FMVSS 106);
“(B) lamps, reflective devices, and associated equipment (FMVSS 108);
“(C) rearview mirrors (FMVSS 111);
“(D) motor vehicle brake fluids (FMVSS 116);
“(E) new pneumatic tires (FMVSS 119);
“(F) tire selection and rims (FMVSS 120);
“(G) motorcycle brake systems (FMVSS 122);
“(H) motorcycle controls and displays (FMVSS 123); and
“(I) glazing materials (FMVSS 205).
Source:
https://www.congress.gov/bill/114th-con ... l/685/textbnc