One of the features to Android Auto is the promise of a semi-walled garden. Google controls what apps work in Android Auto, and what can be shown on the screen as to create the safest possible ecosystem in which phone and car can interact. As we've seen exploring all of the apps available for Android Auto, this isn't a perfect system. On top of the occasional usability bug, Android users who have grown accustomed to the open and modular nature of the OS find the head unit display to be more than a little limiting.
A way around this was always going to happen, and now it has. Pioneer AVIC units have had their security stripped and the ability to install modded versions of Android Auto onto these aftermarket head units.
On a high level, this is a huge win for consumers who want to do more than the manufacturer intended with their hardware.
The AVIC Development Mod alters the behavior of the SD Card in the head unit, making it possible for anything compatible to boot instead of the factory software. This not only means Android Auto can be expanded with things like themes and alternate user interfaces — it also opens the door to install Android Auto on Pioneer AVIC hardware that didn't initially come with it installed. It also means access to features like Wifi, which might have been disabled by Pioneer in your unit for whatever reason, potentially could become available to you at some point in the future. As is often the case with these sorts of things, it's up to the modding community to sink its teeth into this and see what is possible now that all the locked doors have been removed.
On a high level, this is a huge win for consumers who want to do more with their hardware than what the manufacturer originally intended. The potential to add Android Auto alone to other devices is awesome, especially if it ends up working smoothly. Obviously this also opens up a significant avenue of risk, especially when you consider the unstable history of third-party ROMs that have been cobbled together without access to the source code. The potential for something to go wrong leading to a distracted driver performing triage while doing 65 mph on the highway is shadowed only by the potential for a less-than-reputable installer to offer you a killer deal on what is now dangerously insecure and potentially fully exploited aftermarket gear.
There's no reason to be concerned about something like the recent Jeep hijacking demo happening with these Pioneer units, but some of these aftermarket kits can be connected to quite a bit more than the speakers. In very much the same way that a rooted Android phone can be exploited, this in-car system is now highly vulnerable. If you're installing something like this by yourself, there's probably not a ton to worry about. If you're having someone else do it for you, anything could happen. You can head to the AVIC411 forums for details, and if you're feeling brave there's a step by step for trying things out for yourself.