The link to is a blog spam article that makes is it appear as if the Tesla was faster than a current Ferrari model but in reality, it was an 8-year old model. I don't see a lap time for the Ferrari 488 but the Lamborghini Huracan Performante was much faster: 1:18.73 vs 1:21.49 with Randy Probst. The 2018 Nissan GT-R Nismo was also faster. (https://fastestlaps.com/tracks/willow-springs-streets-of-wil...)
The biggest problem is not mentioned at all - the Tesla can do only about 4 laps (4-5 estimated here https://www.motortrend.com/cars/alfa-romeo/giulia/2019/tesla... but the track tires limit the range further).
PSC2s are optional on a lot of high performance vehicles and in many cases standard with the top performance package.
They are also pretty much as close to a slick tire as you can get without compromising all wet performance. There are tires that are more "barely legal" but there aren't many.
The reason they're so widely offered on performance cars is that they are basically cheater tires. They're street legal and grip like hell, but they also cost a lot, make a lot of noise, wear incredibly quickly, and can't be used in cold temperatures. I'm not aware of a single car sold with them as standard equipment which doesn't also offer a less insane tire as an add-on.
Basically they're used so automakers can get good numbers, no one in their right mind actually daily drives these tires. The PS4S used in the original test is generally regarded as one of the best tires for a daily driven performance car.
Just the testament of the driver.
It's bogus.
What was done with a software upgrade? We have zero meaningful measurement of what the software upgrade alone achieved because they changed so much in addition to it.
The time improvement is on the order of what would be expected when adding tire width and softness.