"Progressive" springs are available. I got a set from RockAuto a few years ago.

Supposedly for larger loads, I couldn't tell a difference.

 

thanks for comments on my coil spring issue. yes its same 2008, mexican built 2.4 automatic HHR LT, with stability controls and 4wheel abs, but rear drum brakes.
all stock. added pic of broken spring to my gallery.
...so i ordered stock moog (cheapest!) rear coilsprings. quite cheap considering my local vendor said pair is 155euros (=195USD!).
MOOG CC81063 Coil Spring (8708.80.9100) € 23.41

 

Is this the broken spring ? Maybe I'm looking at it wrong, but where's the broken part of it ?

 

yes, its at bottom of the spring. look closely

 

OK. Now I see it.

 

Yup that's a noise maker! Nice deal on the replacements!

 

On my last rear brake adjustment, I noticed both my rear springs are broken at the bottom. I'm not surprised with the amount of driving I do (227,000KMs to date), I picked up a used pair that appear to be in good condition. Do I need to use a spring compressor to take them out?

 

No spring compressor needed. Easy job. Just don't let the rear axle hang down too far when you take the shocks loose or you could damage the brake lines.

Probably a detailed thread on this site somewhere. I'll take a quick look and see if I can find it. Or try the Search function if you need the info.

 

Have a look here

General Suspension How to Install springs - Cobalt SS Network

The HHR thread the pictures are removed

 

Thanks for the thread, now I know what I'm into. Looks like I'll be installing the
snow tires at the same time, tis the season.