Is moisture under my driver's side floor mat antifreeze?

Moisture under your driver's side floor mat could potentially be antifreeze, especially if there's a leak from the vehicle's cooling system. However, it could also be water from rain, snow, or spills. To determine the cause, check for a sweet smell (indicative of antifreeze) and inspect for any visible leaks under the hood or beneath the vehicle. If you're uncertain, it's best to have it checked by a professional.