Gnarlyness need not be about metal or even fiberglass or carbon fiber. A spirit of fine workmanship must infuse a gnarly object. In this world, even a knit Ferrari can be very gnarly indeed. This is why we dig the underside of a Galaxie rocket car even when it is standing still:
Look at the beautiful finish on the leaf springs. And at the triangular truss structure bracing the live axle. Beautifully worked, mindfully executed.
It's too bug-like and too big not to give me the heebie-jeebies.
Its ability to negotiate uneven terrain, abrupt transitions to split-mu surfaces, and the occasional random kick blows my mind and makes me admire all the people who scored A's in our mechanical engineering dynamics classes back in undergrad.