What is one consequence of driving under the influence of drugs?

Driving under the influence of drugs significantly impairs a driver's reaction time, which is a critical aspect of safe driving. When a person is under the influence, their ability to respond swiftly to changing road conditions, other vehicles, pedestrians, or hazards is compromised. This delay in reaction time can lead to serious accidents as the driver may not be able to brake or maneuver out of dangerous situations in time.

In contrast, the other choices do not accurately reflect the effects of drug impairment. For instance, decreased fuel efficiency is not directly associated with drug use, heightened self-awareness is generally diminished under the influence, and improved driving skills would be contrary to the evidence of impairment that drugs cause. Thus, the most relevant and accurate consequence of driving under the influence of drugs is the impairment of reaction time.