A reader wrote to the Columbus Dispatch explaining to “Car Talk” hosts Tom and Ray Magliozzi that she and her boyfriend took frequent 150-mile round trips in her Toyota Yaris, during which he insisted on turning off the car at every stoplight. She noted that this tactic infuriated other drivers and resulted in a decrease in fuel efficiency, and asked them if shutting off the engine at stoplights was a good idea.
Tom noted that the loss in gas mileage with her boyfriend at the wheel was likely due to his driving habits. “[It’s] probably because he’s got a lead foot the rest of the time. He likely accelerates harder than you do, and drives faster. And that’s costing you more in mileage than he’s saving by shutting down the engine at stoplights.”
Ray pointed out that modern vehicles that shut themselves off at traffic lights are equipped to handle frequent starts, and agreed with Bevacqua that turning off their car at every stoplight could eventually lead to a costly repair bill.
“Engineers say stop/start technology can add about five percent to fuel economy, depending on how much stop-and-go driving is done,” he explained. “But the cars that come equipped with stop/start features have something your Yaris doesn’t have: heavy-duty starters that are designed to make hundreds of starts a day rather than the five or 10 starts your starter typically handles.”
He went on to recommend that they only turn off the engine when they will be immobile for two minutes or longer, not every time the vehicle comes to a stop.