Probably at least once, you’ve had the experience of someone walking up to you so quietly that by the time you noticed you were there, they were close enough to startle you.
Most likely, they weren’t trying to sneak up on you, but a person walking naturally tends to be relatively quiet.
Now imagine that a car could do that — a car that runs without an engine, so that it can move as quietly as a person walking, or even quieter.
As it turns out, that is what happens when you take the engine out of a car. At high speeds, of course, cars generate enough wind noise that you can’t mistake them, and even at moderate speeds, you are sure to hear the sound of the tires on the pavement. At low speeds, though, a hybrid car in electric mode can be as quiet as a person walking — and an electric car can be even quieter. What is more, as tires become more efficient, cars will be still quieter. If you think you can be startled by a person walking up to you, imagine how startled you will be when a car brushes by you at 15 miles per hour, going so quietly that you don’t hear it until after you see it.
This becomes a safety issue if a driver doesn’t see a pedestrian and the pedestrian doesn’t hear the car coming. To reduce this risk, the new electric cars make a kind of chirp at low speeds so you can hear them as they approach. Congress has now voted to make that mandatory, after engineers study the issue and determine how much sound is needed and what kind of sound is effective. We’re not talking about the beep-beep-beep alarm of a garbage truck backing up, obviously. The objective is to make an electric car louder than the sound of a person walking, but not necessarily as loud as a car that has an engine.
Even when car operating sounds become mandatory, though, there will be a way to disable them. Whether doing so is legal or not, it is something some people, perhaps just kidnappers and assassins, will want to do. There is little doubt that the electric car will quickly become the car of choice for certain stealthy characters in Hollywood movies, and it is worth considering who else might like the idea of sneaking up on someone in an electric car.