The benefits of eco-guidance extend to other cars on the road, offering comparable emissions reductions to following vehicles.
Drivers following a vehicle that implements eco-guidance were found to have equivalent reductions in emissions.
Made Public Date


United States

Impact of Automated Vehicle Eco-Approach on Human Driven Vehicles

Summary Information

Eco-approach technology, systems that are designed to achieve environmentally friendly driving behaviors within a Connected Automated Vehicle (CAV), is recognized for its benefits to energy efficiency, with studies showing reductions of up to 20 percent in a vehicle's energy consumption. However, it is not well understood how these benefits transfer to other vehicles on the road. A driver who is following a CAV that uses eco-approach technology is likely to perform many emissions-reducing behaviors simply by responding to the vehicle in front of them.

This study sought to examine such impacts. Using the driving simulator software PreScan, subjects drove through a virtual roadway with multiple signalized intersections.

Four different scenarios were tested:

  1. A base case where the driver was the only vehicle on the road.
  2. A case "with CAV" where the driver follows a computer-driven vehicle that automatically implements its eco-guidance.
  3. A case "with guidance" where the driver's vehicle displays suggested eco-guidance.
  4. A scenario where the driver's vehicle is a CAV that automatically implements eco-guidance.

Each scenario was tested fifty times, and fuel consumption was calculated based on acceleration and speed data.


Both "with CAV" and "with guidance" scenarios resulted in significant reductions in fuel consumption, with emissions reduced approximately 6 percent compared to the base case.
  • The "with CAV" scenario differed from the "with guidance" scenario by only 0.3 percent, a difference that was not found to be statistically significant.
  • The scenario where subjects drove a CAV that automatically implemented eco-guidance was found to be the most efficient, lowering emissions by 10.8 percent compared to the base case and approximately 5 percent compared to the "with CAV" and "with guidance" cases. All three differences were found to be statistically significant.
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