Uber is launching a service in London that lets you share rides with strangers for a cheaper fare

Uber is preparing to launch its UberPOOL feature in London. The service allows customers to book a ride to a destination and reduce the cost by sharing part of the journey with a stranger who is traveling in the same direction.

Uber describes UberPOOL as "the cheapest way to use Uber." It's not going live immediately, though, but will launch at 4pm on December 4.

The main selling point of UberPOOL is the lower price: Uber says it's much cheaper than a black cab, or a standard Uber. That's because several different paying customers share the same vehicle and driver.

Here's a chart from Uber showing the difference in cost between UberPOOL, Uber, Addison Lee, and black cabs:

UberPOOL isn't going to roll out across the whole of London just yet. The company says that it's going to start taking requests for the service from central London and Heathrow Airport to start with.

Here's where it's going to work in London:

Uber is currently facing a big challenge in London. Transport for London, the authority that looks after services like black cabs and the London Underground, has proposed several new rules that could seriously hurt Uber. One proposal is a compulsory five-minute wait time before an Uber driver can pick up a passenger, and another possible option for TfL is banning the display of Uber's cars on the map inside its app.