Cruise Control and Fuel Efficiency: How It Works and When to Use It

In an era of fluctuating gas prices and increasing environmental awareness, maximizing fuel efficiency has become a top priority for many drivers. While modern vehicles boast an array of advanced technologies designed to optimize fuel consumption, such as auto stop-start, cylinder deactivation, and electronic fuel injection, one feature that often goes overlooked is cruise control. Although primarily viewed as a convenience feature, cruise control—particularly adaptive cruise control—can actually contribute to better fuel economy when used correctly.

The Evolution of Cruise Control

The concept of maintaining a constant speed without continuous pedal input dates back to the early days of automobiles and tractors, which featured hand throttles that allowed drivers to set a desired speed. However, these early systems couldn't adapt to changing loads, such as steep inclines, and risked stalling the engine.

True cruise control emerged in the 1950s with Ralph Teetor's "Speedostat," which Chrysler introduced as "Auto Pilot" on the 1958 Imperial. This system used a bi-directional screw-drive connected to the throttle and speedometer cable to maintain a constant speed, regardless of hills. Other automakers followed suit, with GM utilizing a similar technology for decades and various manufacturers employing vacuum-operated throttle servos.

Modern Electronic Cruise Control and Adaptive Cruise Control

Since the 1980s, electronic cruise control has become the norm, replacing unreliable vacuum servos with integrated systems that use speed sensors at the wheels, transmission, and engine to accurately maintain a constant speed. The most recent development, adaptive cruise control, takes this technology a step further by using cameras, sonar, or lasers to monitor the distance and closing speed of the vehicle ahead. This allows the system to automatically adjust the vehicle's speed to maintain a safe following distance, even in stop-and-go traffic.

The Fuel-Saving Benefits of Cruise Control

A study conducted by Volvo and the National Renewable Energy Laboratory in Gothenburg, Sweden, compared the fuel efficiency of vehicles using adaptive cruise control to those with manually regulated speeds. The results, published in IEEE Intelligent Transportation Systems Magazine in June 2019, showed that consistent use of adaptive cruise control led to a 5 to 7 percent increase in gas mileage compared to human throttle management.

This improvement in fuel economy can be attributed to several factors:

• Maintaining a consistent speed: By avoiding unnecessary acceleration and deceleration, cruise control helps optimize fuel consumption.
• Reduced average speed: Vehicles with adaptive cruise control tend to drive at slower average speeds, as they follow the pace of the vehicle ahead, which is often traveling more slowly than the set speed.
• Minimizing human error: Cruise control eliminates the fuel-wasting habits of some drivers, such as rapid acceleration and hard braking.

When to Use Cruise Control for Optimal Fuel Savings

To maximize the fuel-saving benefits of cruise control, it's essential to understand when and where to use it effectively. Cruise control is most efficient when traveling at highway speeds, as it helps maintain a constant velocity and reduces the need for frequent accelerator input. However, it's less effective in stop-and-go traffic or on winding back roads where speeds fluctuate frequently.

It's also crucial to avoid using cruise control in adverse weather conditions, such as heavy rain, sleet, or snow. While modern vehicles equipped with traction control and adaptive cruise control may disable these systems automatically in poor conditions, older vehicles without these safety features risk losing traction if the wheels spin faster than the vehicle is moving.

Other Fuel-Saving Technologies and Techniques

In addition to utilizing cruise control when appropriate, drivers can take advantage of several other technologies and techniques to improve fuel economy:

• Automatic stop-start: This feature, which shuts off the engine when the vehicle is stationary and restarts it when the accelerator is pressed, can result in a 5 to 7 percent increase in fuel economy, according to AAA.
• Proper tire inflation: Underinflated tires can significantly impact fuel economy, with the Department of Energy reporting a 10 percent fuel economy penalty for tires at 50 percent of their recommended pressure.
• Judicious use of air conditioning: Running the air conditioning can reduce fuel economy by more than 25 percent, so it's best to open windows to cool the car initially and pre-cool the interior of electric vehicles before driving.
• Efficient driving habits: Adopting a smooth, steady driving style and avoiding aggressive acceleration and braking can improve fuel economy by up to 33 percent compared to more aggressive driving.

The Bottom Line

While cruise control has long been viewed as a convenience feature, its potential to improve fuel efficiency—particularly in the case of adaptive cruise control—should not be overlooked. By maintaining a consistent speed, reducing average speeds, and minimizing human error, cruise control can contribute to a 5 to 7 percent increase in gas mileage when used appropriately.

However, to truly maximize fuel savings, drivers should combine the use of cruise control with other energy-saving technologies and techniques, such as proper tire inflation, judicious use of air conditioning, and efficient driving habits. By adopting a comprehensive approach to fuel efficiency, drivers can save money at the pump, reduce their environmental impact, and extend the life of their vehicles.