While automakers sketch out a world of sleek and silent electric cars or even self-driving pods that are more den than dragster, the all-electric future is further off than it may appear.

Car companies, starting with Volvo last summer, have laid out plans to electrify entire lineups of vehicles. But the fine print makes it clear that the coming decade and beyond will focus not just on massive battery packs powering electric motors, but also on adding a little extra juice to the venerable internal combustion engine.

Increasingly, that juice will arrive in the form of new electrical systems built to a 48-volt standard, instead of the 12-volt systems that have dominated since the 1950s. Simpler than Prius-type drivetrains and less expensive than Tesla-scale battery power, the new electrical architecture both satisfies the demands of cars made more power hungry by their gadget load and enables the use of lower-cost hybrid drive systems.

Earlier proposals to take cars to a 42-volt standard fizzled for cost reasons, but recent regulatory developments and the hardware that will one day make autonomous cars feasible have reignited the urgency.