Have a 2010 HHR LS with 201,000 miles on it. Month ago redid all the suspension(struts assy,stabilizer links,shocks,brakes and rotors.) Recently when driving on the highway for 10 minutes at 60-70mph slight vibration in front but more apparent when you step on the brakes and the left front side of the car violently vibrates. It will reproduce at lower speeds after that and go away after stopping for a bit. The front left drive shaft has been replaced with new one this past weekend. Tires rotated but problem still exists. I heard the hub assy could be the cause. When bearings go bad I thought they make a loud noise increasing in volume the faster you drive. I'm baffled could anyone lend me some insight I dont want to keep replacing things one by one.

 

Lower control arms. Rear bushings are probably shot at that mileage.
2nd would be the steering shaft. Take a look for any free play.
Might as well look at the steering rack and tie rods too. They could be worn also but my bets on the LCA bushings.

 

I check the tie rod ends they were fine. I also check for play and its tight. If the lower control arms bushings were bad I wouldn't think it would do no matter if car has been driven or not. This seems to be a issue after the car has been driven and front end heated up for 10 minutes

 

Did you at least look at the rear brakes, they need to be adjusted.
At 201K I can guarantee the OE LCA bushings are trash.
Could be hubs, also a guarantee for OE parts.

 

Let's see. I've been on this site a long time. 8 years. Listened and helped out folks with similar problems. Can't tell you how many times that members find those LCA bushing worn out. The OEM bushings and the HHR's suspension geometry are a factor in their short life span.
But what do I know. Just a former automotive tech with a little experience and knowledge. Guess I'm done.

 

The ten minute thing could be the rear brakes heating up, that will cause a shake if the lca bushings are shot, they’ll shake.
I have gone through the entire front end on my 07, LS
The worst shake was from my bushings and from my upper engine mount