The world’s second-biggest economy, which has vowed to cap its carbon emissions by 2030 and curb worsening air pollution, is the latest to join countries such as the U.K. and France seeking to phase out vehicles using gasoline and diesel. The looming ban on combustion-engine automobiles will goad both local and global automakers to focus on introducing more zero-emission electric cars to help clean up smog-choked major cities.

The long-promised software will update Tesla’s existing semi-autonomous driving features, and will include speed matching technology that will help Tesla cars to keep pace with traffic, switch lanes, and exit and merge onto freeways, among other uses ... The speed-limiting software will kick in on roads and non-divided highways, where Teslas will have no choice but stick to the precise speed limit. On freeways, however, Tesla will merely stick to its overall speed limit of 90 miles per hour.

car companies -- most obviously Tesla, but also...General Motors... BMW... and Nissan... are putting their money, and reputations, behind electric vehicles ... With technology improving -- especially for batteries -- prices are falling. Tax breaks, particularly in China, are helping sales. ... In the next 25 years, gasoline consumption will drop 0.2 percent... While the number of passenger vehicles will double to 2 billion by 2040 ... the amount of oil we use for cars will be lower than today

Norway...has become an unlikely proving ground for the proposition that electric cars are ready for prime time. Because of big tax breaks, they have come out of nowhere to seize a third of the new-car market in just five years ... The cars are especially clean in Norway, where most of the electricity comes from dams, not from burning fossil fuels. But even in countries that burn coal for power, the cars are so efficient they can cut greenhouse-gas emissions by more than half.

How much cleaner are electric cars than the fossil-fuel powered alternative? The answer depends on exactly where you charge the batteries ... on average they’re 40 percent to 50 percent cleaner than those that fuel from gasoline or diesel ... While an electric vehicle on average may produce as little as half the pollution as a gasoline or diesel car, there’s great variation within the range. Running on battery power in China was just 15 percent cleaner than a fossil-fuel car last year,

Surveys show that many potential electric-vehicle customers are held back by "range anxiety," the concern that an EV won’t go far enough, that it will run out of juice just when they need it. Range anxiety already makes little objective sense. Research shows that even the modest 2013 Nissan Leaf, with its range of 80 miles, can cover 87 percent of the daily trips ordinary Americans make. That’s more than enough for a second car, or a first car for someone who mostly relies on walking and transit

it’s not as though Tesla’s rivals are standing still. In addition to GM’s Chevy Bolt, Nissan will produce a second-generation Leaf with the same 200-mile range and approximately $35,000 price; it will come in 2017. Before that, Toyota will deliver its Prius Prime, a plug-in hybrid; and BMW already has its pure electric i3. The other major carmakers are piling in as well by the end of the decade.

Other big cities, including New York and San Francisco, have said they intend to use more renewable energy, but San Diego is the first of them to make the pledge legally binding. Under the ordinance, it has committed to completing its transition and cutting its greenhouse gas emissions in half by 2035 ... Officials said they would also shift half of the city’s fleet to electric vehicles by 2020 and recycle 98 percent of the methane produced by sewage and water treatment plants.

Electric cars do have a slightly higher carbon footprint in the manufacturing stage, and each BEV also requires manufacturing a battery. But it turns out the vast bulk of auto-related carbon emissions come not from manufacturing but from operation — driving — and the savings BEVs represent on that score make up the difference by many multiples. (Disposal emissions are similar for both types of cars, and a small percentage of the total.)

Rules governing autonomous driving barely exist, and the few that are in place vary by state. There was nothing stopping Tesla from flipping the switch to make its cars steer themselves, but there’s no system for regulating what that means in the real world. Musk advises caution and responsibility, but Tesla isn’t rushing to rein in drivers ... Tesla owners already are posting videos of themselves driving with theirs hands off the wheel, sometimes ... nearly steering into an oncoming car.