How Green is the Future of Self-driving Cars?

Experts predict self-driving cars will make up 75% of vehicles on the road by 2040. Research has been around for more than 40 years, but the concept is now within reach as executives at top companies such as Google, Tesla Motors, and Mercedes-Benz, amongst many others, plan to launch self-driving cars by 2020.
Currently transportation accounts for about 26% of total US greenhouse gas emissions, the second largest contributor after Electricity. With a wave of driverless vehicles imminent, the big questions is: Will these cars reduce or increase emissions?
“If you have a fully autonomous car that talks to other cars and traffic signals, then it can drive more smoothly, much better than a human can, and there will be fuel economy benefits coming out of that.”
Dave McCreadie Ford Motor’s General Manager of Electric Vehicle Infrastructure and Smart Grid
The assumption is that by eliminating congestion, driving will be more efficient, thus reducing carbon emissions. These cars are designed with image-capturing technologies, allowing the vehicle to scan the surrounding environment to make good driving decisions, which seems to be the main focus of the production of these vehicles - not an environmental focus.