You have been doing research in all the wrong places. Most parts books are WRONG. Many list both.
My theory is that some parts guy assumed that the last 2 digits of the part number indicate the length, which is incorrect in this case. 12 inch "fit" but are not correct for HHR of any flavor.
The factory installed the 9.86 inch part. We call it 10 inch, because it is easier. Actually it is 25 cm being that the HHR uses metric.

 

Lotsa 9.85 inch in this list, and 11.8 inch also. I’ve installed Delphi 11.8 inch links, they didn’t hit the LCA’s or anything, they gave up at 15,000 miles. Donbrew is correct , install the 9.85 “

https://www.rockauto.com/en/catalog/...+bar+link,7580

 

when I pull up the part with vehicle specs at the parts store they only show 12" for 2009 2LT

 

wasnt anything wrong with the links other than it ripped out of the strut bracket, the joints are still intact and free.... not sure why it happened but Ill know more tomorrow after I get done at the shop.
But the 10' and 12" are confusing me on the links as everything is showing 12" on part websites?
Ill make sure to bring this up to the shop tomorrow>

 

Most parts palaces show parts the wholesale sales want them to sell , even if it’s wrong! I got the 11.8 inch links as a test to confirm fitment! Remember the FE5 ball joint problem and stamped steel LCA’s from G5 and Cobalts instead of aluminium ones!

 

Had me curious now, went out to measure and these appear to be 10" center to center

 

Yes it does appear that way.

 

Yes sir, and this site and members have been great with helping to verify/clarify these issues. Hopefully I can get there in the morning without issues. Gonna take the backroads ( stay off the highways ) and leave before rush hour, if the tire happens to give Ill just use my free towing for the rest of the trip.

 

Uh, it is bent. Straightened it would be closer to the 12 inch.

 

uh, tape is not centered.... compensated.