From all of the forum threads that I've read across the web, coupled with talks with various pundits (Tesla, User Experience, Lawyers, etc.) - perhaps two reasons why Tesla has not released 6.0 is due to the following: 1) Liability issues: by this, if Tesla were to introduce a vastly improved (and likely very different) interface into the car, what would that mean in terms of Tesla owners getting into their cars and finding out once they are out driving, that the controls don't work like they did previously - and particularly if there are new features and functions or dramatically changed existing ones. Think of the lawsuits from Tesla owners and other victims, if the change would cause accidents and such. While many of us are fanboys and look forward to change, many others would assume that how they drove the car on Monday is how it'll drive on Tuesday. There would need to be a full system in place to educate drivers and also have them accept the changes (and learning on the road isn't an option). 2) User Experience: somewhat of an issue here. Yes, there's a 17" inch screen in the car, but boy, Tesla does not make it an intuitive experience and one where form follows function. As an example, having so much of the text on the screen in a gray scale makes it hard to read in dim light - such as radio stations. For those individuals (and i'm not one of them), light gray on dark gray isn't the best. Same with temp controls and many other controls. Also, why the notion that we need 50% of the screen for two functions? Radio.... probably only needs 20-30% screen space (having the album cover really big isn't a big value), instead, I'd rather have easier access to radio, Slacker, other media, etc. - instead of having to tap three or four times to go from playing a playlist to going to a radio station. And then to have the temp controls at the way bottom, yes - they are out of the way, but should be more usable. The icons used for changing temp, etc. on the screen aren't the best and aren't best practices from a user experience perspective.