I installed the mudguards recently, and it was an opportunity to see under the chassis for the first time. Not wanting to miss an opportunity to check some stuff out, I took some measurements to get an idea what we are dealing with here. There is just not much info on these cars so you have to take things into your own hands.
As we hear all the time here Volvos aren't sporty blah blah blah I am actually pretty happy with how mine drives and I like me some sporty cars. The SPA platform is relatively new, has a totally new suspension with double wishbones up front. The S60 is at least the smallest and sportiest model based on the platform. I had been sort of curious if the hardware matches how it feels to me. I took all the raw measurements with tape measure and digital calipers and calculated a close approximation of the spring rates. These are all estimates, so take with a grain of salt, but hey it's better than nothing.
2019 S60 T6 R-D with sport chassis
Front wheel rate: 225 lbs-inch (takes spring rate and motion ratio into account)
Front sway bar is: 25.85 mm (measured with digital calipers, no idea if that would be a 25 or 26 mm sway bar officially)
Front sway bar wheel rate: 360 lbs/inch
Rear wheel rate: 241 lbs-inch (this is a very rough calculation due to transverse composite leaf spring is complicated)
Rear sway bar is: 21.65 mm (21 or 22?)
Rear sway bar wheel rate: 153 lbs-inch
Analysis: These numbers are eerily similar to my experience with Subaru suspension tuning philosophy. Moderately stiff springs with a good amount of anti-roll bar. Different than typical BMW tuning with very soft springs. The rest of the tuning is in the shocks which are unknown but feel to be valved pretty aggressively, probably mostly rebound damping as is popular with OEMs. The spring rate is also affected by bump stops but due to the dust covers I cannot measure those on the car. Despite the name "bump stops" most modern suspensions are actually relying on the engagement of bump stops early in the stroke to supplement main spring rate. I'd want stiffer springs, in my fantasy world, with the S60 approaching 4000#. Something like a 275-300#.
Coincidentally...I was watching the savagegeese YouTube series on the development of the Miata (really excellent BTW). In the video on the NC generation (https://www.youtube.com/watch?v=bslB_4JIKs0&t) Dave Coleman of Mazda talks about how they dealt with being forced to use the RX-8 as the basis for the Miata. Much of the chassis was too "heavy duty" for the little sports car, they did a lot of work to lighten the subframes, suspension arms, uprights, wheel bearings etc. What I realized watching this...was that is why the S60 is so heavy! The SPA chassis was developed for the XC90, S90 etc. From what I can see cross referencing a few parts, the suspension hard parts are generally the same. And the stuff is beefy looking under the car. The rear suspension for example has a huuuuge lower arm with provisions to support an air spring where our S60s have a transverse leaf spring. Volvo clearly doesn't have the budget to create specific parts for the -60 series, and it's hardly a labor of love. So we are stuck with a "heavy duty" car and the weight that comes with it.