Yeah, 0W20 is ONLY to meet CAFE standards. (MPG)
(Corporate Average Fuel Economy is aiming at about 49.6 mpg in 2025).

But I don't want to really get into it here as many don't do anything outside what is RECOMMENDED (because of CAFE standards) in the manual.
Oil is "supposed" to be based on temperature and operating conditions, but only in the USA are they going crazy.
You can read what some say about both sides here.
Oil viscosity


Little off topic...
They basically want to eliminate the gasoline internal combustion (Then diesel) engine it seems. And make it prohibitively expensive to own/maintain a vehicle.
(Yet our asphalt roads are paved in black gold/oil)

I am in the construction industry... and they even have an all-electric backhoe.
https://www.casece.com/northamerica/...v-project-zeus