Buyers tend to look at price, safety, and gas mileage when shopping for a car; a question that rarely comes up at the dealership is how well a car seat stands up to years of butt sweat. But even if it isn't a priority for car owners, the vehicle testers at Ford work to ensure the cars that leave the factory can accommodate the sweatiest passengers.

The secret to Ford's durable seats is a device called the Robutt. This video from the car company shows a Kuka robotic arm pushing a buttocks-shaped cushion into a car seat. To replicate a person sitting in the car after exercising, the dummy butt is heated to approximately human body temperate and pumped with half a liter of water. The average person produces about 0.7 to 1.5 liters of sweat in one hour of intense exercise, and people who are especially fit perspire 1.5 to 1.8 liters in the same time.

The sit test is repeated 7500 times over three days—simulating one decade of someone driving their sweaty behind home from the gym. If the surface of a car seat can make it through all that abuse without any wear and tear, the design is good enough for a Ford vehicle. Robutt-approved seats were first introduced in the 2018 Ford Fiesta and are now being built into all Ford vehicles in Europe.

You can watch the messy process play out below. Here are some more robots that, like the Robutt, were designed for oddly specific tasks.