Testing a temperature gauge sender

Right, I have a new sender for my temperature gauge and before I install it I would like to know it is going to be better for my gauge than the one in the car already.  Thing is the one in the car already seems to work but registers only a tiny amount of movement when the car is hot.  Could be the car runs cold which is why I wanna checkout the new one first.

Any ideas as to how to trial the new one would be appreciated.