Final answer:
By law, you must drive slower than the posted speed limit if conditions such as road construction or bad weather make the posted speed unsafe.
Step-by-step explanation:
By law, you must drive at a safe speed, which may be slower than the posted speed limit if conditions such as road construction or bad weather make the posted speed unsafe. In other words, it is your responsibility as a driver to adjust your speed according to the existing conditions. This is to ensure your safety and the safety of others on the road.
Leave plenty of space between you and the car in front. Always lock your doors and wear your seatbelt to protect you from being thrown from the car in a crash. Be aware of your surroundings — pay attention. Check your mirrors frequently and scan conditions 20 to 30 seconds ahead of you.
Eventually, even a slight increase in speed causes a much faster fuel burn. That's the reason why the optimal speed is generally between 40 and 55 mph for most passenger cars, whereas larger cars, like SUVs and trucks, are more efficient at slightly lower speeds.