A month or so a tear-down of the Chevy Volt was performed, disassembling it down to the nuts and bolts. I was able to listen in on a presentation by the team discussing what they found. Namely, over 100 microprocessors in different parts of the control systems. That's a heck of a lot of CPU's, and apparently a higher percentage than is typical in "normal" gasoline powered cars. The majority of these CPU's are in the BMS and other control systems for the electric part of the system.
My writeup of the presentation:- Chevy Volt teardown reveals future battery pack upgrades and safety monitoring systems
Have collected all the videos here:-