“I can sum it up, from Day 1 to now: It’s never finished, it’s always an experiment,” Mr. Zimmer said recently in a phone interview from London. “We’ve been trying to create sounds which are aesthetically pleasing and calming — sort of anti-road rage.”

So don’t expect to hear the growl of an overtuned V-8, the bark of an amplified exhaust, the screech of tires digging for grip. Mr. Zimmer wants to take you to a different place. “It’s something that transports you in the most elegant way possible,” he said. “We are trying to make your life less chaotic, more beautiful.”

But beyond aesthetics and marketing, enhancing an electric car with sounds is a legal issue as well. In the United States, the National Highway Traffic Safety Administration adopted rules in 2018 that say electric cars must make some artificial sounds. Congress made it a requirement that light-duty hybrids and electrics emit noise as a safety measure for pedestrians, bicyclists and people with a visual impairment.

The European Parliament has mandated that electrics sold in Europe will have to “sound similar” to cars with combustion engines at speeds below 20 kilometers an hour. The rule is to take full effect in 2021.

So far, BMW is alone is hiring a composer with Mr. Zimmer’s repertoire, and this work is a labor of love for the 62-year-old, German-born musician. He said the Bavarians “came to me” to accept the work, “although a half-hour later I had an email from another company to create something for an electric car.”