New cars are coming equipped with more and more sensors that are, ostensibly, designed to help drivers stay safe. Some autonomous cars currently being tested have to help “see” the road. All of this makes a regular car wash nearly-impossible, and , that means automakers have to take a lot of extra precautionary measures to keep their robot cars clean.

The obvious everyday things drivers encounter on the road make it easy for an advanced autonomous car to suddenly be rendered blind. The same goes for tools and brushed used in a regular car wash.

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A traditional car wash’s heavy brushes could jar the vehicle’s sensors, disrupting their calibration and accuracy. Even worse, , which can cost over $100,000, could be broken.

A self-driving vehicle’s exterior needs to be cleaned even more frequently than a typical car because the sensors must remain free of obstructions. Dirt, dead bugs, bird droppings or water spots can impact the vehicle’s ability to drive safely.

So automakers and self-driving tech developers are coming up with both ingenious and basic methods to tackle the problem.

Toyota, and Uber rely on regular old humans to wash a car by hand using microfiber cloths blotted with rubbing alcohol, water or glass cleaner, CNN reports. When there’s snow or ice, Uber has an employee use a squirt bottle filled with windshield washer fluid to clean camera lenses, followed by a puff of air to remove the lingering residue, according to CNN.

In the end, the solution that’s almost certainly going to be necessary is tech that’s built to clean sensor equipment on its own. Google’s self-driving car unit Waymo showed last year how it uses , and CNN reports that General Motors’ Cruise is currently building sensor cleaning equipment of its own.

Other startups, like May Mobility, told CNN they simply rely on a cloth and water and wash the entire vehicle by hand. .