DETROIT — Fiat Chrysler and Peugeot agreed Wednesday to merge into a single company that will become the world’s fourth-largest automaker, a giant that could bring consumers a wider variety of cleaner vehicles at a faster pace, including more powered by electricity.

The boards of the two companies signed the deal to achieve what neither was good at alone: conquering the challenges of stricter emission rules and navigating the transition to battery-powered and autonomous vehicles.

The new company, which doesn’t yet have a name, will be led by Peugeot’s cost-cutting CEO Carlos Tavares. Fiat Chrysler CEO Mike Manley will stay on, though it was unclear in what capacity and for how long.

For consumers, the agreement will give Fiat Chrysler access to “multi-energy platforms” already developed by Peugeot, including electric vehicles, Manley said.

“That obviously increases choice and improves overall fleet performance from a CO2 perspective,” he said. “In any competitive environment, you win because you offer your customers great value.”

But don’t expect to see Peugeot sedans in the U.S. anytime soon. Tavares said the combined company’s brands would stay where they originated.