Uber, facing a backlash from riders and drivers over its carpooling service, is now guaranteeing arrival times for its Los Angeles customers — or $2 off their next UberPool trip. If the experiment works in LA, Uber says it expects to roll it out in additional markets.

Uber says that because the app "shows you the absolute latest time you’ll reach your destination, you will often arrive well before the estimate shown." Which seems to suggest that Uber is padding its estimates so it won't have to discount too many future rides. The "Arrive By'' estimate customers see factors in additional passenger pickups by drivers, as well as traffic and other variables. Uber says it will be using its own technology, rather than any third-party apps, to receive real-time traffic data — but a spokesperson wouldn't say anything beyond that.

This is Uber's latest effort to build support for UberPool, which is facing mounting criticism from drivers and riders alike. Last month, the company announced that UberPool rides in Manhattan would be a flat $5 during peak hours. And the company's top executives routinely describe UberPool — in no uncertain terms — as the future of transportation.

"Of course, carpooling is not a new idea. But we finally have technology — the smartphone in your pocket — that can instantaneously match people headed in the same direction at the same time," Uber CEO Travis Kalanick wrote in a Wall Street Journal op-ed yesterday. "And when getting a ride is cheaper and easier than looking for your keys, your directions, your car and a parking space — well, why bother to own a car at all?"

"carpooling is not a new idea"

The problem is, many drivers and a lot of riders don't like UberPool. Riders complain that the app often defaults to UberPool, when they would rather use UberX, or that some of the detours to pick up additional passengers take them too far out of their way. Drivers say UberPool isn't worth the headache of consolidating multiple riders in one trip for a smaller payout. And they say riders often take out their UberPool frustrations on them by giving them negative ratings.

Uber says it hears all these complaints and is trying to craft a better system. And despite appearances, the service is apparently doing just fine: the company says over 100 million pool trips have been taken "around the world" and that over 100,000 people take pooled trips every week in 18 cities globally, including New York, Los Angeles, Beijing, and Shanghai. And in China, where Uber is losing $1 billion a year fighting its competitors, UberPool has grown to over 30 million trips a month.