While learning about towing, and ultimate additional cargo capacity weight limits I think I've come across reasons why the HHR's capacity restrictions ought to be closely adhered to.
Besides the somewhat anemic brakes and the facts that the engine power, transmission integrity under extremes, and cooling abilities of both aren't really rated for heavy duty involvements, there is -ANOTHER- engineering 'just enough' that doesn't seem to be indicated very often.
I think that the rear wheel hub/bearing assemblies simply aren't up to a circumstance that would approximate loading up to -and- beyond the somewhat meagre totals of weight & towing capacities of the 1/4-ton truck (1000 lb. MAXimum) that is bandied about.
If you look at the rear beam/axle wheel bearing-hub engineering in a literal sense, the 'rear axle' is severely limited in it's supported dimension of -really- only about six inches -total;- on each side, (if that) . This -lack of support- for a load, at the extreme ends of an 'about' 5 foot beam, with the added leverage of the wheel assembly added to THAT extreme end, is pretty telling in it's own right.
It is hardly surprising that rear hub/bearing assemblies (no matter the ultimate quality of materials & manufacturing) have a comparably short life span. And if an operator is lax in their determining loads to the upper degree, degradation/failure of wheel bearing/hub assemblies is hastened even further.
Also, the wear/failure properties shouldn't be viewed -exclusively- to those rear 'axle' components, since the front end is even lighter in the engineering department, and is subjected to even higher stresses due to much less bearing area coupled to the steering loads (much! higher under braking too !) .
In My Opinion, anyone willing to subject this comparatively light-duty truck to anything approaching/exceeding published load ratings had better not find any room to complain about accelerated wear and/or failure of bearing points at the wheel/hub/bearing aspect of the car.
For reliability sake, now that the (new-to-me) vehicle is still -alive- at this 140,000 mile mark, and with no known history of the wheel bearing/hubs (ALL-around) having been -freshened up- , this is (yet-ANOTHER) the -next- aspect of this car that will be meted appropriate money-infusion before I'll consider the 'reset-of-the-clock' as being adequately addressed.

 

It is mostly braking power. The Feds regulate capacity labels. The HHR is classified as a 1/2 ton truck A 3/4 ton truck has much beefier brakes.
It is really a classification thing, not a real limit.

 

Don’t try to simplify it. It’s an issue with too many unknowable variables to determine a limit with any degree of certainty.

Except when they say no trailer, GM’s default trailer towing capacity is 1000#. Low and arbitrary. That’s like 4 big passengers.

GM says zero trailer for all manual HHR’s. Zero trailer for all HHR SS, despite much better breaking, more power, and lower ratios than LS/LT.

Why? Cuz Wesayso? Nah. They have their reason, and they’re not telling.

 

That and you need to cut the bumper cover on the SS to install hitch, sacrilege!!

 

Three words come to mind;
Plausible, Practical, and In Theory (ok technically 4)

Safety first. And for the general population that means "no tow".
Can it be done? Of course with limits.
A couple kayaks or paddle boards and bulky beach gear on a light weight harbor freight type trailer. Yes
A pallet of pavers for the backyard patio project? No bueno

Respect the weight of your tare and behave accordingly.

 

If you must tow, buy a pickup truck.

 

I have never heard anyone say "towing with FWD is the best way to tow". Ever notice how few FWD trucks there are?

 

Lol! They are getting hard to find.

Amen. What are they gonna do if you violate the rules now? Void your warranty?

The only reason I can think of for allowing towing with a 2.2 auto but not manual is clutch capacity/life.

The only reason I can think of for allowing towing with a 2.2 auto but with any 2.0, is too much power, leading to problems with driveline capacity/life.

 

It is not GM that sets the weight limits. The government/industry sets class specs. If they wanted it to tow more they would have made a 3/4 ton vehicle.
Nobody is testing to failure. They are not saying the car is not capable; they are saying you could get a ticket if you exceed.

 

huh, that is interesting, note to self if I buy another HHR to avoid those. I love my trailer I restored for mine so much. https://imgur.com/a/xpYHDEd
But I think I am buying a truck when she dies, unless my property burns down and I have to move. Already had 2 fires within 50 miles this summer...