Not so sure..my unit will arrive on Monday so just ask for how
is it like 
..according to the supplier for the unit Im
getting:
"Dashboard Dyno, and quarter mile timer, and brake tester
and suspension analyzer. Everything you need to tune your cars
performance As you accelerate, the GTech meter is measuring power,
speed and distance, and memorizing your 0-100, 0-400m, speed and
peak power.
The heart of the GTECH/Pro is a precision silicon accelerometer. An
accelerometer is a sensor that measures acceleration, also known as
G-Force. G-Force is what's keeping you in your seat as you are
reading these words and if it wasn't for the seat you would be
accelerating to the ground at 1G (32 feet per second per
second).
G-TECH/Pro measures your speed and distance traveled by integrating
acceleration over time. Basically, if you know how fast you are
accelerating for a certain time period you'll know how much your
speed has changed after that time period. So, if you start of from
zero speed then you'll know what your speed is after every time
period. These time periods are very small (2.5 milliseconds) and
that's how G-TECH/Pro maintains its accuracy."