Connected and Automated Vehicles (CAVs) could change our transportation industry for the better. Not only can they help to address issues with traffic congestion and human error, but they can also have positive environmental effects. From reduced fuel consumption to lower emissions, CAVs could be a valuable asset in restructuring transportation and promoting eco-friendly alternatives.

Environmental Benefits of CAVs

Operating a CAV can be better for the environment than a vehicle driven by a human. According to “A Review on Energy, Environmental, and Sustainability Implications of Connected an Automated Vehicles,” CAVs with vehicle connectivity can select optimal routes to save energy. Speed harmonization and trip smoothing can reduce the amount of braking and acceleration that a vehicle undergoes during a trip, and smooth starts and fewer speed fluctuations can also help.

All of these measures can amount to significant fuel savings. Pairing partial automation and connectivity could reduce a vehicle’s fuel consumption by 5 to 7%.

The results are even greater when considering the savings an entire fleet of vehicles might see. Experiments have found that corporate communications between CAVs can reduce fuel use by up to 13%, while also reducing CO2 emissions by up to 12%. Introducing a CAV into traffic with the goal of minimizing unnecessary braking and acceleration can result in all of the traffic reducing fuel usage by 40%.

Carefully structuring the travel of multiple CAVs can further increase fuel savings. Synchronizing two or more CAVs following each other, a process called platooning, helps to reduce aerodynamic drag and increases the efficiency of every vehicle in the line. This strategy is most effective at high speeds, making it ideal for highway travel, particularly for fleets of heavy-duty trucks. A study found that a 3-truck platoon could experience a 10 to 15% reduction in fuel consumption with platooning when traveling 50 miles per hour.

A vehicle’s weight closely correlates with its fuel economy, and CAVs offer a unique opportunity to reduce vehicle weight. When CAVs have expanded to encompass most of the on-road traffic, it could be possible to remove some of their safety equipment, because they would help to eliminate human driving error. With less safety equipment, vehicles would weigh less. Studies have shown that reducing vehicle weight by 10% can also improve fuel economy by 6 to 8%. Plus, with less weight, CAV powertrains could be reduced, too, saving another 5% in fuel consumption.

CAVs are naturally a great pairing with electric powertrains. A study led by the University of Michigan found that electric powertrains can be key to reducing greenhouse gas emissions. The study found that CAVs with electric powertrains have lifetime gas emissions that are up to 40% lower than the emissions produced by CAVs with internal-combustion engines. Internal computing systems in CAVs can also help to reduce energy use and emissions.

CAVs benefit the environment in other ways, too. According to “A Review on Energy, Environmental, and Sustainability Implications of Connected and Automated Vehicles,” CAVs can park in much tighter spots than traditional vehicles with human drivers can navigate. This can help to avoid the construction of additional parking lots. Parking lot construction releases emissions, and CAVs can help to prevent this. Ultimately, if CAVs help to eliminate the need for obsolete transportation infrastructure, those elements could be removed, allowing for increased urban development.

Potential Downsides

While CAVs can help save energy and fuel, there are downsides to these vehicles that can negatively affect the environment. The “Review on Energy, Environmental, and Sustainability Implications of Connected and Automated Vehicles” reports that CAVs are equipped with devices that consume energy, including sensors, radar, and high-speed internet connectivity devices. These devices draw power from the vehicle, increasing the vehicle’s energy consumption and reducing its overall energy efficiency.

As CAVs are proven to be safer, restrictions on top highway speeds for these vehicles may be lifted. That in itself could negatively impact the fuel economy these vehicles see. Increasing top speeds from 70 to 80 miles per hour also increases a CAV’s energy use by 13.9% per mile. Driving at speeds that are above a vehicle’s optimal speed can decrease fuel economy by 5 to 22%, potentially negating many of the positive effects that these vehicles offer.

CAVs require significant communication and data processing, and large-scale data centers provide the computational resources needed to keep these vehicles running and communicating. All of this infrastructure draws significant energy. As CAVs become more popular, electric vehicles will require more charging stations.

While CAVs can help save fuel and reduce emissions, they may also encourage vehicle occupants to travel more miles than they would otherwise. Researchers at the U-M School for Environment and Sustainability note that this behavioral change, called the rebound effect, can occur because people feel like they can make good use of their time in the vehicles by reading or working. Since travel time becomes productive time, people may be willing to travel farther, spending more time on the road and putting more miles on their vehicles. If this behavior change is widespread, it could result in a net increase in energy consumption with CAVs, negating these vehicles’ energy savings.

Looking Forward

CAVs have the potential to benefit the environment, but only if we carefully structure their operation to maximize those benefits. Implementing the use of procedures like platooning and continuing to regulate top highway speeds for CAVs can create situations where the benefits these vehicles offer are well-utilized. Encouraging vehicle sharing, robotaxi fleets, and other measures that promote shared travel can help to fight the potential issue of people traveling longer distances in their own CAVs out of convenience. CAVs stand poised to dramatically transform the transportation industry, reducing its negative effects on the environment. We will need to be vigilant in implementing and regulating these vehicles to ensure that those positive benefits stay effective.