Hello group. I just purchased an opia2 GPS Mouse. It always reads about 12 or 13 miles per hour under the actual speed I'm doing. These wrong readings I keep getting are while driving in the country or in the city. I've had it placed on top of my dashboard and windshield in various places and no matter what I do I keep getting the wrong readings. My firmware is v2.6 but I'm not sure if a firmware update would have anything to do with my existing problem. Can anybody help me? Thank you!