Are you talking about the ones with carpet? I wouldn't. I use a small rug shampooer.

Somebody spilled a big cup of coke on my car mat. When I got home I remove the mat, washed the carpet by splashing soapy water on the carpet side and scrubbing with a scrub brush, then rinsed it off with the garden hose using a strong stream of water. Then I left it to dry in the sun. Next day it was clean and dry, looks perfect.

Thank you for your responses.

We clean ours at the do-it-yourself car wash places. Clip the mats on the wall and go at them with those super water power hoses, soap first and then rinse.

I put the rubber-backed ones in the washer and dryer.

They come out looking great every time.