Nuvi 3790T issues and concerns

[kevindd992002]

1.) Is it normal for the device to have a louder volume/more clear TTS voice when it is plugged in to the car mount (external source) rather than when it is powered by battery?

2.) When I check the ODOMETER data while driving, why does it seem to be innacurate? It displays more kilometers than the actual driven distance. Say for example I just drove around 0.1 Km, the unit gives me a reading of 1 Km already in the screen! Is this normal? Or does the last digit in the speedometer data stand for a decimal?

Thanks in advance for your help