Just so you know, there is an issue with the radiator cooling fan assembly on the HHR/SS. Mine overheated last week after hitting 253 degrees.....the dealer fixed it and the part is on backorder also. Took a few days to come in. They have had quite a few SS come in for this reason. The fans just stop working intermittently and then finally stop working all together. Just giving you a heads up.That may be your issue....maybe not..... I picked up last Friday and promptly traded it in on Saturday. Besides this issue, there have been too many problems with the car for me since day one.
Oh and GM wont cover it under Powertrain warranty....its only covered under the 3yr,36,000 warranty so if your over 36,000, they wont warranty it for you...... I fought with GM customer service because it does cool the engine which is the powertrain but they would not hear it.....they just dont get it.

 

X4

 

in texas mine runs 203 when its 100plus outside. when driving it stays around 190ish. js

 

Mine will get up to 218. Dealer wont even look at it. They say it is within spec.

 

I do belive they are right.

 

Mine seems to run a little hotter when I am in the boost.
Boost equals hp hp equals heat.
With the Turbo upgrade you are almost in the boost all the time If you are accelerating.
So it does seem to run a little hotter.
On a 85-90 degree humid day it varies from 194- 205 highway.
But caught in slow traffic I have seen 210 and 215 once

 

Take out the jumper / extender wire set between the fan and the engine and direct connect the plugs, you may have to cut a wire tie. I know of at least 4 hhr's where this jumper burned and the fan worked sometimes. The plug on the jumper burnt inside.
This jumper is about 6 inches long, with a plug on both ends.
I found this after I changed the fan out. And the problen started again 4 weeks later.