Top 10 Unusual Car-Washing Tips Published on June 22, 2018 in Top 10 by The Car Guide 2. Cola for washing your windshieldIs this an urban legend or a real car-washing tip? One try should convince you. Place a towel at the bottom of your windshield, and then pour cola on it. The bubbles will act tough on grime. Obviously, you need to rinse the windshield completely afterwards.