Some buyers love hybrid cars because they barely use any fuel to achieve the same goals as some of the gas guzzlers. As hybrids become increasingly popular, there are more of them on the road. While this may be better for the environment and the wallet, there is a hidden danger that isn’t seen but heard, or instead not heard. 

The first hybrid car was built back in 1899 by none other than a 23-year-old Ferdinand Porsche. The Lohner-Porsche Mixed Hybrid was the first vehicle to include a battery and gasoline for power. It used an internal combustion engine to rotate a generator that supplies electricity to the wheel hubs of electric motors. The car could travel almost 40 miles on battery alone. 

Can you hear the sound of a hybrid?

Fast forward to today and no longer are hybrids limited to small odd-looking slow economy cars like they used to be. Today’s hybrid comes in all forms, cars, trucks, SUVs even Semi trucks. And with all of their forward-thinking, the same problem plagues them all. You can’t hear them coming.

Scientific American shared that in experiments led by perceptual psychologist Lawrence D. Rosenblum of the University of California, Riverside. Blindfolded subjects listening to car recordings approaching at 5 miles per hour could spot the recognizable Honda Accord internal combustion engine 36 feet away. But they did not identify a Prius running in electric mode until it came within 11 feet — shortening their reaction time to less than two seconds before the vehicle reached their position. In other experiments where additional realistic background noise was added, the Prius zoomed by without detection. 

What are manufacturers doing to fix this?

Adding sounds to a hybrid seems like an easy fix. The question becomes, what kind of noise? Some have recommended a chirp or beeping sound, but that has shown to be more distracting to others. Everett Meyer of Enhanced Vehicle Acoustics in Santa Clara, California, says the best sounds for alerting pedestrians should be carlike. A sound similar to the gentle purr of an engine or the steady tire roll all over the roadway. This type of sound can be matched to the speed and acceleration of the vehicle. 

Ford designs for sound

It’s not just the safety of the pedestrians to keep in mind either. When the new Ford Mustang Mach-E arrived, designers knew it needed to sound like a Mustang too. Jim Farley, Ford’s president of new businesses, technology & strategy, said “We spent so much time making the sound feel modern,…when people drive this vehicle zero to 60 (mph) in three seconds, they are going to say ‘Holy cow!'”

As the hybrid market continues to expand, the need to make hybrids safe and enjoyable to drive will likewise continue to evolve. While some think adding sound is disingenuous to the driving experience. The reality is, most won’t even notice the difference. The addition of familiar sounds will help keep driver, pedestrian, and passenger all in the same frame of mind.