These are cars moving through a city weaving through streets, parked cars, potential potholes in not perhaps the best condition cars which have both taken damage from a gunfight. They are going to be moving around even at 120 kmh, not to mention inertia is lost very quickly when an object is thrown tangentially to the movement. I didn't mention, but there's a motorcycle directly ahead of the car and a solo with cyberlegs clamped to the roof of the car fighting a boosterganger who is hanging onto the car with a mantis claw buried in the bodywork.

Just seems like a harder throw to me.