A mobile wireless device conditionally disables device functionality when a driver is detected to be the user while in a moving vehicle. The device comprises sensors for sensing: motion, thermal images, and a vehicle cabin side. A processor is configured to perform a method including detecting whether the device is traveling within a moving vehicle; capture thermal image data points at multiple spatial locations; and render spatially binned thermal image data from the image data points. The processor is further configured to invoke a driver in possession mode of operation of the device in response to determining that: (1) the device performed the capturing while located in the front seat of the moving vehicle, by applying a front seat thermal image signature definition to the spatially binned thermal image data, and (2) the device is located on a driver side of the moving vehicle.