Electric cars are quieter because they do not have a combustion engine constantly firing, vibrating and moving lots of mechanical parts. At low speeds, that can make them noticeably quieter than petrol or diesel cars.
But completely silent? Not quite. EVs still make noise from tyres, wind and other moving parts. At lower speeds, they are also required to make an artificial sound so pedestrians can hear them coming.
What makes a petrol or diesel car noisy?
A combustion engine creates power through thousands of small controlled explosions. That process involves pistons, valves, gears, exhaust gases and plenty of moving mechanical parts. All of that creates sound and vibration.
An electric motor works differently. It uses electromagnetic forces to turn the wheels, with far fewer moving parts and no combustion happening under the bonnet. The result is a much quieter drivetrain.
So are EVs silent?
No. Even without engine noise, tyres make sound as they roll across the road, air moving around the body creates wind noise, and suspension, cooling systems and electric motors can also be heard.
The faster you drive, the more important tyre and aerodynamic noise become. An older European Environment Agency overview notes that propulsion noise can be substantially lower, while tyre and road noise become increasingly important as speed rises.
That means the biggest difference tends to appear when an EV is moving slowly around a city, car park or residential street.
Why does my EV make a strange sound at low speed?
That slightly futuristic hum is probably there on purpose. Because EVs can be very quiet at low speeds, regulators became concerned that pedestrians, particularly people with visual impairments, might have difficulty hearing them approach.
That led to AVAS, or Acoustic Vehicle Alerting System. In the European Union, new types of electric and hybrid cars have been required to use AVAS since July 2019, with the requirement extending to all new vehicles of those types from July 2021.
AVAS creates an audible sound while the vehicle is moving slowly. Engineers made the car quiet, then gave a little of the noise back. For a good reason.
Does AVAS have to sound like an engine?
Not exactly. European rules set requirements for the sound produced by AVAS rather than simply telling manufacturers to copy a petrol engine.
That is why different EVs can sound very different at low speeds. Some hum. Some whirr. Some sound slightly like a spaceship arriving somewhere very calmly. The important part is that pedestrians can detect a nearby vehicle.
Could electric cars make cities quieter?
Potentially, particularly at lower urban speeds. The European Commission highlights reduced noise as one benefit of fully electric vehicles.
Road noise is not a small issue. The European Environment Agency says transport noise affects millions of Europeans, with long-term exposure linked to sleep disturbance and other health effects.
Replacing every combustion car with an EV would not make city streets silent. Tyre and road noise, heavy traffic, buses, motorcycles and delivery vehicles would remain. EVs remove an important source of noise, the combustion engine, rather than every source of traffic noise.
Is a quieter cabin another benefit?
Often, yes. Removing engine noise can make the interior feel calmer, particularly during slow driving and acceleration. But it can also reveal sounds you previously did not notice.
Without an engine covering everything up, tyre noise, wind noise or the occasional cabin rattle may suddenly get your attention. Quiet cars have a funny way of making small noises feel very important.
Questions, answered.
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Why are electric cars quieter?
Electric cars do not have a combustion engine producing continuous engine and exhaust noise. Their electric drivetrains have fewer moving mechanical parts, so they produce less propulsion noise.
Are EVs completely silent?
No. Tyres, wind, electric motors, cooling systems and other components still create noise.
Why do electric cars make a humming sound?
At low speeds, many EVs use an Acoustic Vehicle Alerting System (AVAS). The artificial sound helps pedestrians detect the vehicle approaching.
Is AVAS mandatory in Europe?
Yes. EU rules require AVAS on new electric and hybrid vehicles covered by the regulation.
Are EVs still quieter at motorway speeds?
The difference becomes smaller as speed increases. At higher speeds, tyre and wind noise make up a larger share of the sound produced by any car.
Quiet, yes. Sneaky, no.
Electric cars are quieter because one of the noisiest parts of a traditional car, the combustion engine, simply is not there.
At low speeds, the difference is so striking that EVs deliberately make a little noise to ensure people know they are coming.