All electric cars manufactured in the European Union and the United States will be required to emit a sound that warns of their presence on the road from 2019. The measure affects all vehicles that can be driven by an electric motor, whose weight is less than 4.5 tons. It affects both those moved only by batteries, including motorcycles and mopeds, and hybrids, plug-in hybrids and hydrogen fuel cells.

The measure was approved in the European Parliament in 2014 and will be mandatory for all electric vehicles that come on the market as of July 2019. As of 2021 this obligation will be extended to all models. In the United States this obligation was approved much earlier, in 2010, but the law was not drafted until 2016, and will apply from September 2019. Some of the vehicles on the market already emit this sound at low speeds, which, in many Sometimes it is disconnectable. So do both the Renault Zoe and the Nissan Leaf, for example.

According to the European Regulation the sound will be emitted by the vehicles, obligatorily, when they circulate at a speed inferior to 20 km/h (30 km/h in the United States) as much forward march as reverse. The device will be disconnected by the driver by means of a switch. The system will be activated again when the vehicle starts again. Vehicles equipped with a combustion engine will disconnect the sound when it starts operating. At higher speeds, the rolling noise is sufficient to identify the presence of a vehicle, so it will automatically disconnect.