Uber says customers are enthusiastic about the ride-hailing company's newest option — Comfort Electric — which allows them to summon a ride in a Tesla or other premium electric car.

There's only one problem: Some Uber riders can't figure out how to operate the door handle of a Tesla, which lies flush against the car's body.

It's an unexpected wrinkle in Uber's effort to get more drivers and riders to go electric.

Driving the news: Axios is first to report that starting Tuesday, Uber is expanding Comfort Electric to seven additional cities: Austin, Baltimore, Denver, Las Vegas, Philadelphia, Portland, and Seattle.

The big picture: Uber says it's committed to becoming a zero-emissions mobility platform in the U.S. by 2030 (and globally by 2040).