Simply put. The iPhone 5 will not work on your M3.
See.
http://www.engadget.com/2012/09/18/a...hone-5-review/
Superficially, it's hitting all the right marks, but Lightning comes up short in a number of important areas. It is, of course, incompatible with the roughly 350 million billion iPhone and iPod accessories currently on the market -- a problem mostly rectified by a $30 adapter. But, that's not a perfect solution, as even that won't support iPod Out, the specification used in some cars (most notably BMW and Mini) to enable in-dash control of an iPod or iPhone.