The document in the link in Reply #18 describes a single message (and a compound or extended message). But it says nothing about the interstices between messages.
I suspect that reading a real data stream byte by byte would be illuminating. IIRC in another automotive-related Thread that I helped with there was a minimum interval between messages.
This system will have been designed to be robust in a very noisy environment. I find it very hard to believe that it relies on continuously interpreting every single byte correctly.
...R