I too went for the Broidit
http://www.dsldevelopments.com for my iPhone 5S.
I have:
- Brodit Volkswagen Golf VII Brodit ProClip Center mount 2013 AND
- Brodit 514435 Adjustable Holder Cable Attachment with Lightning to USB Cable for Apple iPhone 5/5S
The lip on the clip doesn't actually grab the rear of the vent which is it supposed to do, but none the less is does remain securely in place - it hasn't fallen off once in over a year - which is a lot more that I can say for the old TomTom iphone 4 mount I used on my old car.
There is more that one Adjustable holder that fits the iPhone 5s - depending on whether you keep it in cover or not and also how big the cover is. Also there are other mounts available, including one for the vent to the right (UK) of the steering wheel.
I use mine with an official Apple Leather cover and it slips into the holder easily and connect to the lightening connector.
Note you need to supply you own lightening cable and only the official Apple ones will fit.