Old helicopter collision behaviour: - 0 - 18km/h, no damage - 18+km/h, take away a minimum of 15% health, increasing with speed That wasn't working well for ground driving, where hitting obstacles would quickly deplete health. New rules: - 0 - 25km/h, no damage - 25+km/h, take away a minimum of 5% health, increasing with speed Damage from high-speed crashes remains the same.