I'm sorry to be that guy, but yes a raspberry pi is definitely powerful enough and fast enough to run a vehicle, and yes, Adam's pi is controlling the engine. The low-level MCU that was mentioned is interpreting the instructions from the pi's calculations into machine code. The pi cannot natively interpret CAN. There's a ton of MPU's in the vehicle, and they all communicate via the CAN network. The pi is so much more powerful than the native unit that it can calculate algorithms inside machine learning software while simultaneously updating the system with the new instruction set. The raspberry pi is 100% controlling the system. It is the central processing unit. The difference between that and the standard ECU in your vehicle is that the entirety of the instruction set from your ECU is at most 3MB, and clocks in at a top speed of 128MHz. The Raspberry Pi 2 from 2015, the time of that article, had 1GB of SDRAM and a clock speed of 900MHz.
"GM stated that the 2011 Buick Regal will have the auto industry's fastest processor: 128Mhz, and 3MB of flash. 'Three meg of flash memory and 128MHz clock speed doesn't sound like a lot in terms of computing power until you consider the environment these controllers have to live in. Our controllers are made to operate reliably up to 260 degrees (127C) and down to -40 degrees (-40C) for the life of the vehicle.'"
It not only can run the ignition system, but it could run the entire car. The reason we still use these systems is because of 1) bureaucracy 2) simplicity 3) My personal opinion, money.
I've heard arguments for and against CAN, and I personally believe those in favor of can are just afraid of change. I think it's time to move into the future. CAN is the reason why we still use these crude ECU's, where bandwidth is limited, speed is limited, possibilities are limited. It cost money to develop new technologies, but that's what drives innovation. We've had access to ethernet for decades, and that would give us access to more powerful computer systems to run our vehicles. You wouldn't need to tune your car, because it would do that for you. Finely demonstrated by Adam, with not very powerful computer.