Just one autonomous car out of 20 vehicles can significantly alleviate traffic congestion, according to research from the University of Illinois.  The culprit behind many traffic jams is the variability in speed of human drivers — waves of excessive braking and acceleration that can cause long backups.  By avoiding jackrabbit starts and sudden stops, a more even driving pace inserted in the traffic flow by an autonomous car dramatically reduces variability-induced congestion.  What’s more, according to the research team fuel consumption is reduced by up to 40 percent when averaged across all the cars in the traffic flow.

Fortunately, it may not take very long to gain these advantages — more uniform driving can be accomplished with relatively simple control systems (think intelligent cruise control augmented by automated braking).  A completely autonomous vehicle is not required.