I've used brodit kit before. Admittedly not for iPhone but Samsung galaxy s4 but kit was really sturdy and well built. It's a bit pricey but definitely a case of you get what you pay for.
I use a Kenu Airframe+ for mine. Simple and effective.
http://www.amazon.co.uk/Kenu-Airframe-Portable-Mount-Smartphone-Black/dp/B00LU5LWQK
Got one. Tried to use in my Audi with the circular vents. Could not figure it out or get it to work.
I use a Kenu Airframe+ for mine. Simple and effective.
http://www.amazon.co.uk/Kenu-Airframe-Portable-Mount-Smartphone-Black/dp/B00LU5LWQK