When should cruise control generally not be used?

Cruise control should generally not be used in the rain because it can reduce the driver's ability to respond quickly to changing road conditions. In wet weather, traction can be compromised, and using cruise control might prevent the driver from adjusting their speed effectively to maintain control of the vehicle. When it's raining, road conditions can be unpredictable, leading to conditions such as hydroplaning, where the tires lose contact with the road surface. In such situations, it is critical for the driver to remain highly alert and capable of making quick adjustments to speed without the automation of cruise control.

In contrast, while it may be less advisable to use cruise control in heavy traffic or on steep hills, there can be specific situations where it might still be used cautiously. Heavy traffic typically requires more frequent speed adjustments, making cruise control impractical. Similarly, on steep hills, cruise control can cause the vehicle to accelerate uncontrollably downhill or struggle uphill, which is why it’s often advised to turn it off in those scenarios. However, in calm weather conditions on highways, cruise control is considered appropriate and beneficial for maintaining a consistent speed.