The Economist has a discussion of economics inside the VW Group, and compares its brands with other brands — including Tesla.
Porsche is small but highly lucrative
Volkswagen’s sports-car brand could be worth a fortune
[...] Porsche is a tiny cog in Volkswagen’s machine. It made 253,000 cars in 2018, out of 10.9m vehicles at vw as a whole. And it will sell 20,000 Taycans a year, compared with millions of id cars. But it makes so much money for vw that some investors and analysts suggest only spinning it off would recognise its true value.
[...] Porsche’s handsome returns rely in part on sharing the cost of developing new models across the wider group. The Cayenne’s underpinnings, for instance, are the same as vw’s Touareg and Audi’s q7. Porsche and Audi also plan to share a platform that will underpin several new battery-powered models.