A passenger in the the 1957 Zündapp Janus sits with their back to the driver. The Janus has two doors: the front of the car and the rear of the car.
Janus, the two-faced god of Roman mythology, is the ruler of transitions: coming and going, entrances and exits, the past and the future. It’s appropriate, then, that the 1957 Zündapp Janus is named for him. The only car ever produced by the German motorcycle manufacturer Zündapp, the Janus had two seats, positioned back-to-back so that the driver was looking forwards and the passengers were facing backwards.
It gets wackier: the two doors are not on the sides of the car but on the front and back ends. More precisely, the doors are the front and back ends of the car. The whole thing is extremely symmetrical – the car’s engine is in the very middle, behind the seat backs – and tiny. Being a motorcycle manufacturer, Zündapp had tried to get into the microcar scene by dropping a chassis on a modified scooter motor. It was not very successful, at least in part because there’s a loud and smelly engine directly behind the seats. The company stopped making cars entirely the next year.
You can see a Zündapp Janus in action in this video, 2:22 in: