This app communicates with an Arduino (or similar) via Bluetooth - it processes the data and displays the key information to the driver. The app also communicates with GPS to display the current, average and max speed to the driver. The app processes the data, and uses the data input at the start of a race, to display the information the driver needs to finish the race in the most efficient way possible. All the data - including all the telemetry data from the Arduino; the GPS time, lat, lon and current speed; and a lap by lap breakdown are saved automatically at the end of the race. These text files can be exported via a file explorer or via the built in email function within the app for post race processing. 
This combined with the lap graphing application I have written allows direct comparison of variables related to the car - including battery performance, motor performance and drivers lines and gear changes.
The app also has the ability to calculate amphours if the ability is not present on the Arduino.The app also performs calculations on the data so that the driver knows whether they are using too much or too little power to finish the race and whether they are driving too fast or too slow based on the targets which were entered - along with the display the app also physically speaks to the driver so the driver doesn't even have to take their eyes off the road.
Currently being tested - LIVE DATA EXPORT TO http://www.gptiming.net/livestream-1