European governments are making big promises to ban the sale of cars with combustion engines: Germany by 2030, France and the United Kingdom by 2040. It'll take a lot more than promises, though, to bring about the all-electric future.

The initiatives could become the biggest government-driven revolution in a major market since anti-tobacco legislation — and a benevolent one, given that carmakers get fair warning. But it's easy to tout the end of an era with nonbinding promises, and much harder to get enough people to like a genuine zero-emission car (that is, one whose only contribution to emissions is made by the energy industry as it produces electric power).

Granted, electric vehicles already have a lot of fans. People like the idea of reducing their carbon footprint, as well as electric cars' fast acceleration and noiselessness. Tesla has a big order backlog, and predicted resale values are good: In the most recent German rankings, two of the three electric leaders — the Hyundai Ioniq and BMW i3 — were expected to retain more than 60 percent of their original price after four years. In the United States, 30 percent of buyers consider an electric car, compared with close to zero as recently as four years ago.