Uber cabs use time and distance covered to calculate the fares. That means, if you don't know the short routes to reach certain destination then you will be fooled by most of the uber drivers to earn some extra. In addition to that, if your driver is a really slow driving person and you don't ask him toh speed up a bit then get ready to empty your wallet. Another problem is that you can't your uber ride. I mean you are not able to choose the type of car you want. Spacious or small. But keeping aside all these, uber is cheaper than rented autos if you are careful. Have a nice ride.