Self-driving cars are widely regarded as the answer to traffic congestion, and one of the potential solutions for reducing air pollution, thanks to their ability to communicate to each other and to the traffic infrastructure and share information about their location, speed, and road conditions. They are supposed to be much more fuel-efficient than conventional cars, and are expected to reduce car ownership, which should lead to reduced fuel consumption, but a new study suggests that driverless cars could actually use more energy.
According to a study from the University of Michigan Transportation Research Institute (UMTRI), contrary to what many people would think, self-driving vehicles may consume more fuel, because of one simple fact – they will make more trips. Brandon Schoettle and Michael Sivak, the authors of the study, wanted to figure out how self-driving cars will affect fuel consumption levels, expecting that they will reduce overall consumption, given that they will use energy much more efficiently. But, they came to the conclusion that fuel consumption will actually increase, since autonomous vehicles will make more trips throughout the day, because they will be shared between more household members, and one single car will be used to perform the tasks and errands for every person in a given household.
Within one family, a single driverless car will be used to take the kids to and from school, drop parents off at work and then pick them up to bring them back home, and run all sorts of errands in the meantime, which amounts to more driving overall and more miles covered.
“It could be that sharing the vehicle ends up increasing the mileage because of all these connecting trips,” Schoettle said. “The net effect is probably going to be an increase in mileage, and in general the more miles you drive the more fuel you burn.”
The researchers took data from the US National Household Travel Survey into account, which suggested that driverless cars could reduce car ownership by 43%, but on the other hand, could lead to increased number of miles per vehicle. According to that survey, each vehicle will cover 20 406 miles per year, a 75% increase over the current annual average of 11 661 miles annually.
Another important factor that is expected to contribute to increased fuel consumption is that autonomous driving technology will allow people who usually don’t drive, for various reasons, to start using cars that will be able to drive themselves. This means that self-driving cars will be used by the elderly, minors who are too young to obtain a driver’s license, or people who simply don’t like driving and prefer to use public transit currently, which will undoubtedly increase the number of total miles travelled.
Despite these findings, driverless cars are edging ever closer to mainstream availability, with pretty much all global automakers developing autonomous driving technology, hoping that they will be able to bring a fully-autonomous vehicle to market in about 15 years. For now, car companies like Toyota, Mercedes-Benz, Volvo, General Motors, in addition to tech giants Google and Apple, seem to be ahead in the race to create the first production-ready self-driving car.