Salam
Its 42 L and usually 5 L out of that is kept for reserve. So on auto your tank would take up between 35-37 L of petrol if you fill it when the fuel light goes on.
Also, fill it up on auto and reset the trip meter to 0 and then drive the full tank or half talk or even quarter tank and then refill on auto from the same pump. Note the the distance you travel after the first fill and divide it by the number or L filled in the second fill. You will get your exact average.
