Final answer:
The safest speed at which you should drive is influenced by the speed limit, road conditions, weather, visibility, and instantaneous speed as indicated by your car's speedometer. An understanding of these factors, along with the ideal speed, helps in ensuring safety and fuel efficiency. Adjusting your speed in accordance with changing driving conditions is crucial for safe driving practices.
Step-by-step explanation:
The safest speed at which you should drive is determined by a variety of factors, including the posted speed limit, road conditions, weather conditions, visibility, and traffic. While cars may not always travel at the correct speed limit, it serves as a guideline for the maximum safe travel speed under ideal conditions. It is crucial to adjust your speed accordingly if these conditions are not ideal. For instance, you may need to drive slower in rain or fog due to decreased visibility and increased stopping distances.
Additionally, you should always observe the speed at which you are traveling using your car's speedometer, which measures the vehicle's instantaneous speed, although it may not be perfectly accurate. The ideal speed, which is the maximum safe speed a vehicle can turn on a curve without friction, also plays a role in determining how fast you should drive.
Determining the right speed is not only about law compliance but also about safety for you and other road users. Over 50% of the power of a car is used to overcome air drag at highway speeds, affecting fuel efficiency and vehicle control. The most fuel-efficient cruising speed is often cited as 70-80 km/h (about 45-50 mi/h), a balance between efficiency and safety, as demonstrated during the 1970s oil crisis when maximum highway speeds were reduced. When conditions deteriorate, or when approaching a pedestrian crossing or an area with a recent history of accidents, it is safe to reduce your speed even more to ensure safety.