Few automotive interiors carry as much design weight as the Mercedes-Benz 300 SL Gullwing. Step past the raised door — hinged at the roofline rather than the sill, a solution born from the car’s tubular spaceframe chassis rather than styling whimsy — and the cabin makes its case immediately: saddle-red leather stretched across every surface, a slim wood-rimmed wheel, and a shift linkage so exposed it looks like an afterthought bolted to the transmission tunnel.