I've swapped out my thermostat a couple times now and my car still will not get up to normal operating temperature. It will stay under 1/4 of the way up. On the highway, it is 1-2 clicks above C.

I bled the system after both t-stat replacments and there are no leaks... (when I'm bleeding the system is the only time my motor will get somewhere betwee 1/4 and 1/2 - closer to 1/4 though).

What else could this be?