Their dropdowns are not the limitation
Worth clearing up first, because the name invites the assumption: C: Year Make Model is not automotive-only. Their Basic plan lists unlimited YMM fields, their listing covers bikes, boats, printers, cartridges, tires, wheels, audio and HVAC, and their documentation walks through building dropdowns like Printer Brand / Series / Model. Adding a non-car product line does not force you off it. If you came here expecting a schema wall, there is not one — the reason to look elsewhere is the price ladder.