1) more distinction between various cars at the same (example) 500pp, not that we all finish at the exact same time on the Nurburgring.
2) more immersion (sounds, G-force,) in the clutch, gear, differential department, especially on deceleration.
3) more data telling us about custom tuning, real time. (in practice mode only)
GT7 is still way not close to release, ETA minimum 2 more years. thank the PC gods for pcars this fall.