Hypothetically let's say someone has a accident driving an old car such a Ford Capri......would one expect the police to trawl a hypothetical "former Ford Capri owners forum," asking "what do you think caused the accident" and then using those regarded as giving the most suitable answer as some form of expert witness.
Not as such. But there was a case when a driver on some kind of club run was involved in a serious accident and the police trawled the drivers previous contributions to the club's internet forum for statements that could be read out in court to portray him as a hooligan.