When ordering an Uber in Los Angeles, San Francisco or New York, you may have been hit with an offer to save money using UberPool.
Rather than riding solo, the option allows you to share the backseat with a stranger headed in the same direction who's willing to share the cost.
Uberpool was introduced a year ago, and according to CEO Travis Kalanick, Uber is actually sacrificing profit with the offering, because those riders are spending less money. This from a company that was recently valued at $50 billion.
Read MoreWhat stands between Uber and success in China?
"It's profitable in San Francisco, but not as profitable as a normal ride," Kalanick said Wednesday at Salesforce.com's Dreamforce conference, in an onstage chat with Salesforce CEO Marc Benioff. The idea is to promote "the carpooling thing," he said.
In some cities, more than 100,000 people a week are using Uberpool, he said. "That's two cars becoming one."
Kalanick is trying to beat back the critics, who have jumped all over Uber for everything from surge pricing and overaggressive marketing tactics to lack of concern for rider safety and skirting labor laws.
At Dreamforce, Kalanick chose to focus on the long-term goal of building a giant business—now with 4,000 employees—while making Uber a force for good. By pushing into remote areas around the world and introducing ridesharing in places like Riyadh, Saudi Arabia, and Medellin, Colombia, he's trying to make "transportation as reliable as running water."
Whatever profitability hit Uber is taking with carpooling, it's small on a relative scale. Uber riders around the globe are taking thousands of rides per minute, Kalanick said.
Read MoreSuper Bowl of software descends on San Francisco
It's also just one of many ways Uber is trying to increase efficiency in transportation and reduce traffic. The San Francisco-based company has also been rolling out UberEATS, turning its army of drivers into food delivery people.
"If every car in San Francisco was Ubered, there'd be no traffic," he said.
With 150,000 people swarmed into the city's downtown for Dreamforce, that's a message that resonates.