How much current needed to power arduino uno? I am planning to build an rc car based on arduino uno. I will use 3S 11.1 V Li-po to power whole circuitry. So my question is;

First, can arduino be powered directly with 11.1V from its Vin pin? Would it be a problem or not? If it is OK, then no need to answer the bold part below.

If it is not, then one solution comes to my mind is to use a voltage regulator which will convert 11.1 V to 5 V. But while choosing a regulator, I saw that max output current is one of the important specs. So what is the minimum amount of current needed to run Arduino UNO?
The maximum voltage at the Vin pin is 12V, so using your battery is fine!

Considering the current consumption:
The arduino itself will usually source less than 200mA, but your whole setup will probably sink more than that.