GPS Speed shows approximate speed and direction. Use it when you are a passenger or there is no standard speedometer.

BASICS:
✔ 60/180/540 are switched automatically
✔ Kmh/Mph/Knots
✔ Compass
✔ Timer
✔ Work in background

PRO:
✔ Digital speedometer in horizontal mode
✔ Max & Average speed
✔ Height
✔ GPS signal level indicator
✔ more GPS info and "Copied!" by tapping on signal level
✔ More info about Advanced Features

Continued use of GPS running in the background can dramatically decrease battery life.

GPS Speed HD+ is iPad special version released.
http://itunes.apple.com/app/gps-speed-hd/id463407070