This is yet another post that will be useful to only a few people — sorry to the rest of you! But I found this information a little bit hard to track down, so I wanted to put it out there.
The Audi A5 Cabriolet and S5 Cabriolet come with everything needed to support the voice recognition system (a.k.a. “voice command” or “voice control”) present in other Audis, but it’s disabled by default. I guess Audi thinks it won’t work well enough with the top down or something. That doesn’t seem like a good reason to leave it disabled with the top is up, but who am I to say? In any case, it is possible to enable it, and in my testing it works just fine (in fact, it works better than the older generation of voice recognition in our 2007 Audi A6). I did this on my 2011 S5 — it should work on any A5/S5 Cab with the same MMI system, but I make no guarantees. Obviously, any change you do like this is done at your own risk.
This information is on most of the forums, but I thought it was tricky to wade through all of the threads and find the simple, reliable way to do it (many of the posts explain an unnecessarily convoluted method involving enabling the hidden menu, changing languages, leaving the car to sit overnight, etc. — you don’t need to do any of that). If you have access to the VAG-COM VCDS software, this is very easy to do. If you don’t have access to VAG-COM, I highly recommend getting it either by buying your own cable or finding someone who does. It’s useful for many, many things.
Here’s what you do:
That’s it. Once the MMI is done rebooting, the voice recognition button on the steering wheel should work. Again, do this at your own risk, and be careful poking around in VAG-COM — it is possible to mess things up. Don’t blame me ;)
BTW, the VAG-COM software is Windows-only, but I run it just fine in VMWare Fusion on my MacBook Pro.