"If the info there is as outdated as you say, where could one find a reasonably complete and up to date intro to car computer technology?"

You won't find this in the public. You would need to work in the industry to get access to all the specs. Much of it is under NBA between companies.

' Are there any tools out there that can be used for simulating a car network (CAN bus, ECU etc.) for lab purposes?"

Yes, Vector CANOE is probably the most widely used tool for this. It has a scripting engine called CAPL that closely resembles the C programming language. dSPACE is another one.