The patent filing shows Seres' plans for an onboard toilet that slides out from the bottom of a passenger's seat with a push or through voice-activated commands.

The loo will come with a fan and exhaust pipe to channel odours out of the car, according to the filing on China's intellectual property administration seen by the BBC.

Waste is collected in a tank that has to be emptied manually. The toilet also features a rotating heating element that evaporates urine and dries other waste.

When not in use, the toilet is concealed beneath the seat, making full use of the space inside a car without requiring more room.