Adaptive Cruise Control

Adaptive Cruise Control Ratings


What Is It?

Adaptive (Automatic) Cruise Control (ACC) senses where the vehicle in front of you is relative to your own vehicle, and slows down and speeds up your vehicle to maintain consistent spacing. Unlike traditional cruise control, which can only be set to a single speed, ACC can adapt when other vehicles change their speed.


Why Did ACC Earn a 2-Star Rating for Rear-End Collision Prevention?

There is only one publically-available report on the safety benefits of ACC, and the findings are somewhat limited: if such systems were fully deployed and utilized, it was estimated that the number of collisions on freeways for travel velocities above 25 mph would be reduced by 17 percent for two specified scenarios (highway driving when vehicles are traveling over 25 mph when an ACC-equipped vehicle approached a slower vehicle traveling at a constant velocity, and when a lead vehicle slowed in front of an ACC-equipped vehicle).


Why did ACC Earn a 1-Star Overall Safety Benefit Rating?

The estimates above would correspond to a reduction in the number of police-reported rear-end collisions by about 13,000 in 1996, and this was interpreted as indicating a fairly strong benefit compared to manual driving. However, as a percentage of total crashes of all types, the crash types tested in the one available study account for less than 1 percent of total crashes.


Why Would I Use This Technology?

ACC adjusts the vehicle’s speed in response to other vehicles’ changes in speed. The primary benefit of this technology is that it helps the driver manage speed and maintain a safe distance to other cars. It should be noted that ACC was primarily developed as a convenience, rather than safety, feature.


What Do Drivers Think?

Drivers who already own an ACC system have a very high opinion of it, with 76-93% of survey respondents reporting that they would buy the system again. Nearly half of respondents said that the system helps relieve stress. About a third of respondents said that the system made them a safer driver.


How Well Does It Work?

ACC systems may help prevent 13,000 crashes per year. Surveys suggest (see above) that most drivers are very satisfied with these systems.


Who Benefits Most?

ACC is primarily available in luxury and higher-end vehicles, though this is expected to change in the coming years. The technology is most beneficial to drivers who often drive on highways. It may also improve the driver’s ability to navigate traffic and improve fuel economy, so could be of benefit to drivers looking to maximize gas mileage. 


In What Situations Doesn’t It Work?

ACC systems are not designed to respond to stationary or particularly small objects. Camera-based systems can be affected by the time of day and weather conditions, whereas radar-based systems can be obstructed by ice or snow. Surveys have shown that relatively few drivers are aware of these types of limitations, and may overestimate the system’s protective benefit. Some drivers also have difficulty telling when ACC (vs. standard cruise control) is active.


Mobility Significance

Although ACC’s mobility benefits are relatively minor, the system would help smooth a driver’s control of the vehicle, and allow him/her to focus on other aspects of driving.


Different Names, Same Idea
ACC can be found under various different names, including:
•    Autonomous cruise control
•    Intelligent cruise control


How Can I Learn More?

Full references to all studies quoted above can be found in the official AAA Foundation report, "Evaluating Technologies Relevant to the Enhancement of Driver Safety." The project's Fact Sheet provides more detail on the rating system itself, and the criteria used to assign solid and open stars, both for Overall and Scenario Specific ratings.