ELO ranking

Every driver starts at 1000.

In each race, a driver duels every other driver. Each duel:

ΔELO = K × Factor × (Result – Expected probability)

• Result: 1 if ranked better than the other, 0 otherwise.
• Expected probability: 1 / (1 + 10^{((opponent_ELO – driver_ELO) / 400)})
• Factor: 1.5 if you win the duel, 1 otherwise.
• K: 7 before 30 races · 4 after 30 races if ELO < 2000 · 2 if ELO ≥ 2000
• Bonus: +2 after each race played.
• Eliminations: no duel between two eliminated drivers. An eliminated driver loses every duel against classified drivers.

The sum of ΔELO from all duels is added at the end of each race, plus the bonus.