I bought a universal Ram car mount. Will be the last car mount I buy.

http://www.rammount.com

Edit: this specifically is the one I bought for my M7. It will work for the M8 too.

http://www.amazon.com/gp/aw/d/B006QRHZJK/ref=mp_s_a_1_2?qid=1399301787&sr=8-2π=SY200_QL40