Lanos (hatchback) - Sagging suspension/twisting chassis

[Rodd1s]

(for right-hand drive cars) the right-rear corner seems to sag and sit noticeably lower then the left side or any of the front corners as seen by a difference in arch gap.

I first noticed it on my first Lanos, but only after having the lowered springs put in. At first I figured it's the rear springs being unequal lengths, I swapped them over to find that car sits exactly the same - so, it's not a problem due to sagging springs. The sag was so noticeable I've had police stop me to ask why my car is uneven and whether there was anything broken or missing on the undercarriage.

Not long after I got rid of my first Lanos a friend of mine also bought a 2002 3dr 1.3 hatch - exactly the same as mine, but in black - and it was completely standard, so had original springs and that too had a slight sag on the right-hand rear corner (roughly and inch or so on flat ground).

Now, with my current Lanos, which also still has stock suspension (although is slightly older than my previous one) the same is very apparent, especially when there is a weight in the boot/trunk. Last night I put a pair of 10" woofers in an MDF box in the boot (along with my usual tool bag, which weighs about ~25lbs/10kg) and being parked on near-enough level ground there is a 2 to 2.5 inch difference in arch gap between the right-rear and left-rear corner.

If anything, I thought the left corner would be the one to sag as the damper is blown/leaking anyway.

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My question is, has anyone else ever come across this? If yes, does anyone know a fix or workaround to level the car out?

I'm at the point of thinking that I should get some non-pigtail springs (i.e.: like what's used on coilover type suspension) and cut one shorter than the other. I'm sure you can see where I'm going with this.

Any input appreciated!

[Rodd1s]

Furthermore, as I'm spotting random Lanoses (Lanoo's?) around car parks (parking lots for those from elsewhere) I'm noticing the same on others. Some not as bad, but yesterday I saw one that was very noticeable, again on completely flat ground - ok, the driver was sitting in the car, but there was a clear 2 (maybe 3) inch arch gap difference from left to right.

Seeing the car from one side you'd think the rear has been lowered, then from the other it's just normal...

It's fair to expect that when there is one person in the car it might ever so slightly lean to one side, but no other manufacturer quite as bad as the Lanos in particular.

What's going on?