KPN

The new theory with my Saab guy is head gasket replacement. Any opinions about this?

110K. This is where my Saab mechanic is at...water pump and TB replacement. He and I are both a little reluctant to spend the $$ on a maybe. After market therm, but then when that didn't help, OEM.

Fans are coming on, appears to be no coolant loss.

Heat inside is working fine...

Yes, these were all attempts to solve the issue...the radiator cap has not been replaced. I am not seeing coolant into the overflow bottle above the regular fill line. Timing belt has not been changed.

I have a 2005 Saab 92x Linear with 2.5 l engine..it is basically an Impreza WRX with a Saab interior. It has been overheating on the highway only (speeds over 60 mph). The heat gauge creeps up after 10-50 miles of highway driving, then jumps up as the car slows to a stop. In-city street driving is no problem. Thermostat, radiator and coolant temperature sensor have all been replaced. My Saab mechanic is stumped. Anyone seen this before?