A structured mat that is placed on an automobile's dashboard (and/or the rear window shelf) and provided with a quantity of water, or other suitable liquid, that on heating will evaporate into the interior air of the vehicle. The mat structure includes a water impermeable layer that lays against and partially covers the top surface of the dashboard and/or rear shelf and a fluid wicking layer over the impermeable layer that may be saturated with evaporative fluid (on a repeated basis as necessary) and serve as a reservoir for the evaporative process to be carried out. The multilayered surface may be manually refilled with water (or other suitable liquid) from a hand held container or may be automatically refilled from reservoirs structured in fluid connection to the evaporative surface.