I'm cutting through the dark on a skinny two-lane side road north of Pescadero, Calif., roof stowed, arms jerking wildly around a tiny, non-assisted steering wheel as turn after blind turn fades into vision. It's so quiet, I can hear the tall grass nipping at the carbon fiber fenders as the little two-seater claws out of the curve and dives into the next. I should be in auto nirvana -- the road's empty, there's no posted speed limit. But I've got other thoughts, like how badly I want a Baja-style headlight bar bolted atop this $122,000 Tesla Roadster.

Owners...