Electric cars in the European Union no longer benefit from their signature silent acceleration. Instead, they need to sound like gas cars.

A new law taking effect in the EU Monday aims to improve safety by ensuring that pedestrians—including those who are sight impaired or distracted—can hear electric cars as they approach.

The new law mirrors one set to take effect in the U.S. in September 2020.

The big difference is that the European law will require electric cars to make sounds like one with a gas engine below 12 mph or when backing up. And unlike Americans, European drivers will have the option of deactivating the sounds when they deem it necessary.

In the U.S., the NHTSA is considering a proposal by automakers to develop their own custom sounds for their electric cars. The U.S. law is also set to require car to make noise up to 18.6 mph. Above that, regulators say the cars generate enough noise from wind and tires to be audible.

In the U.S., 50 percent of electric and hybrid cars need to have the system by this September. NHTSA says it expects the new rules to cut injuries by 2,400 a year once they're fully implemented. That's been postponed twice. Congress originally required that it take effect by 2014 but it was then postponed and scheduled to take effect this September. The Trump administration delayed the requirement again after taking office.