That is not uncommon at all and not unsafe if done right. Hard realtime systems are there for exactly that reason. Since you need to dimension everything to worst case scenarios, gains tend to not be as big as with soft realtime systems but there you have it: Dynamically shared resources in critical systems.
I can see Vehicle Stability Assistance systems that also do ABS breaking, but that's not really dynamic resource allocation so much as new solution. Ditto, for sending information over the cars local network.
Can you give an example where something not related to traction is run on the same CPU as the ABS/traction system?
