No I don't have a clue how it works in real life, I've only worked in the motor industry for a few decades and spent more hours on track and proving grounds than I can remember.
A data logger alone does not make telemetry.
You want to take a look at what Motec provide in the real world in this area and then compare which of the two (Forza or GT) comes closest to providing.
http://www.motec.com/i2/i2overview/
The info GT provides in also shown in Forza, however Forza then gives you a hell of a lot more on top of that. Care to tell me how I get tyre temp from the GT data logger for a particular corner?
This is what Motec can monitor (in real time):
Various sensors can be used to measure vital parameters of the engine and chassis. For example:
Wheel speeds
Lateral and longitudinal acceleration
Tyre temperatures
Brake pressures
Engine speed (RPM)
Engine temperature
Oil pressure
GPS
Driver input can also be measured. For example:
Throttle position
Braking force
Steering angle
Source -
http://www.motec.com/aboutdata/dataoverview/
Care to guess which comes closer to providing that in real time or replay?
Scaff