These comparison graphics were posted on Reiza's facebook and they show how close GSC got from reality.
Longitudinal G: Sim x Real
Lateral G: Sim x Real
Telemetry comparison: Speed traces around Interlagos, Game Stock Car x Reality
Longitudinal G: Sim x Real
Lateral G: Sim x Real
Telemetry comparison: Speed traces around Interlagos, Game Stock Car x Reality