so, from what little I know, and I’m absolutely not even remotely a car person:

car electrical systems run at really high voltage with much harder systems than you’d find inside a normal computer, because it’s an extremely noisy environment that has to survive lots of fucked up shocks

and AFAIK the standards are only kinda-sorta standards. interfacing with them is very very hard. im sure this gets easier once you get TO the network, but flashing that shit and changing what it does with the network seems like a pretty tall order. maybe try something on the cellular chip?