For more than a decade, automatic engine start/stop systems were sold as painless climate tech, a clever way to trim fuel use by cutting the engine at every red light. Now the feature is rapidly ...

But does this tech actually do anything? Obviously, an idling engine uses fuel, while an engine that’s off does not. But restarting that engine does use fuel. So which one has more of an impact? Well ...

Start/stop systems are among the simplest ideas in automotive history—turn off the engine when you don’t need it, save fuel, and start again when you do. Passenger cars embraced this decades ago, but ...