Methods and apparatus for determining context of a mobile device are provided. In an example, provided is a method for identifying an environment of a mobile device. The method includes receiving a motion sensor signal. The motion sensor signal can be received from an accelerometer and/or a gyroscope. If a frequency characteristic of an engine is detected in the motion sensor signal, a control signal is output identifying that the mobile device is located in a motor vehicle. The control signal can enable a vehicle navigation mode. The control signal can also be used to alert a user to the identified environment and/or change a feature of the mobile device. The method can also include receiving an audio signal from a microphone, detecting the engine vibration from the audio signal, and using the audio signal to confirm the detecting the engine vibration from the motion sensor signal.