Reducing speed limits neither saves lives nor protects the environment. This is because the more slowly a car is driven, the more time it spends on the road spewing exhaust into the air and running the risk of colliding with other vehicles. The argument's reasoning is flawed because the argument ['fails to consider that if speed limits are reduced, increased driving times will increase the number of cars on the road at any given time', 'neglects the fact that some motorists completely ignore speed limits', 'presumes, without providing justification, that drivers run a significant risk of collision only if they spend a lot of time on the road', 'presumes, without providing justification, that total emissions for a given automobile trip are determined primarily by the amount of time the trip takes']