Hollow or Solid sway bar here is a interesting video

http://www.onallcylinders.com/2017/04/25/video-strength-testing-hollow-vs-solid-sway-bars/

Enjoy!

Have always thought that but now proof. Thanks.
I would think a solid bar might be good for an off road vehicle or racer.
But even in this case hollow is likely better.
On an MK7 the lighter weight is a big plus.

Some geek proof - from Sway-A-Way's web site:

https://swayaway.com/tech-room/torsion-bar-wheel-rate-calculator/

The important point. The polar moment of Inertia (J) rises with the 4th power of bar diameter. This means that small increases in outside diameter make a HUGE increase in spring rate. It also shows that the material in the center of the bar does almost nothing.






Kwheel = Wheel Rate [lb/in]
X = Wheel Travel [in]
J = Polar Moment of Inertia [in4]
G = Shear Modulus [lb/in2]
L = Torsion Bar Active Length [in]
d = Arm Length [in]
Do = Outside Diameter [in]
Di = Inside Diameter [in]

As long as you have the room to get the right diameter bar in there. Also if you have the same diameter bar, solid will be stiffer than hollow. To get the same stiffness on a 26mm rear H&R you need a pretty big OD bar.

This isn't an independent test and compares two different bars. We don't know what the "popular" bar is or how well it's made.

I'd like to see the results of a hollow and solid bar from the same company.

I wouldn't put much weight in a test that's obviously biased toward selling the specific product it's supposedly testing. 6 lbs makes zero difference on a street car - even racing a street car. Heck, I was taking a 6 lb crap while reading that, which has the same net affect