When I talk about communication I'm not meaning exact dates and details of their specific operations...
"Hi, we're building X car, it'll be released as DLC on y day"
"Oh in 3 months there will be an update containing x,y,z"
All I mean is a blog that connects with the players. Replies to their biggest complaints and tells us why things can't be done that we ask for, or why certain things are going to be changed. What they really think about corner cutters without us just guessing etc.
That's the problem, because we don't get told anything people here decide to just make their own assumptions about why x can't be done or why y is late. If PD just talked to us and gave us some insight into what they're generally doing and put their ideas to us you wouldn't have 'unannounced 2.06 changes' threads and complaints about those unannounced changes.
Remember back to whichever update they changed the exterior camera. It wasn't in the change log, they just did it. Then there was backlash and they changed it back in the next update. If they just posted a blog with "our thoughts about the external camera" and got feedback on what they were thinking they could have saved time and effort changing it, then changing it back.
That's what I'm talking about.
Oh and also when there is DLC, promote it. Tease the fans, get the community involved in guessing what the cars are (like Forza does), build the anticipation. don't just put out a press release and short tweet, INTERACT!