Detecting Acceleration in a car (iPhone Accelerometer)

Question

I am working on an iPhone app where we are trying to calculate the acceleration of a moving car. Similar apps have accomplished this (Dynolicious), but the difference is tha

Answer 1

Some thoughts:

• Gravity is a vector quantity, not a magnitude.
• Acceleration due to gravity and acceleration due to some other force are not distinguishable (you also can't able to tell the difference between going around a corner and rolling your car).
• You might have better luck with two accelerometers, but then you'd need two phones.

If it were me, I'd write up a disclaimer that says "This doesn't work on hills, use a straight, level road for testing."

P.S.: I like the cash reward for answers, I'll be sure and post that as a suggestion on meta.stackoverflow.com :P