Masure the speed of GPS and record a variety of acceleration time.
Provide the aids, such as compass, map, etc..
Provide the voice control function. (Only for full version)
PS:
1. Please wait a minute; let GPS to detect enough satellites.
2. Please use the iPhone/iPad with GPS included.
3. The speeds accuracy depends on the performance of GPS. There might be error for the speed and only for reference.