2003 xtype loosing power when it heats up under load 2.1 petrol

SOURCE: after topping coolant levels up and driving for

It is surely a leak ,the coolant can go anywhere like apart from leaking,what is happening is when you are driving it leaks because there is more pressure in the radiator and it leaks somewhere ,why you don't see it,it is because the coolant is so hot and when the coolant when it leaks then hit the engine that is also hot,this make the leak coolant to evaporates very quickly that why you don't see it.Well what you have to do is top the coolant level,let someone start the engine you lift the bonnet standing in front of it,then tell the person inside the car to accelerate up 3000 rpm for near 10 minutes,then you watch carefully the radiator,hose and all the connection for the cooling system you will surely find the leaks where it comes from.Hope that clear your mind and solve it.