It's not only cars, we run a support service for our TV's through our own website, a call centre (in the UK
) but it is by far the facebook page that gets the most hits and through which we respond to customer queries and technical support.
It is the way it is sadly and with large organisations all being a part of the Facebook era then that is how it will stay.
It must be said that Facebook do offer a brilliant service, at least for the business. To replace the forums, it may happen but it will be a sad loss to the forums format if it does.