Dear Sir,
Sorry for the inconvenience of misunderstanding installation AVH-X8750BT for your car,
For your iphone6, it can use 2 ways to install AVH-X8750BT for your car 1) App Radio 2) Mirror Display. These 2 ways can be applied to connect similar to Mirrorlink.
1) App Radio : You have to download 2 applications from Andriod which are1) App Radio 2) App Radio Live.
After downloading, you must ensure you already install your iphone6 at App Radio Live by checking the mark sign at application. After that, you can connect AVH-X8750BT to your iphone6 by cable. Please note this way can be commanded at AVH-X8750BT screen.
2) Mirror Display : You must have 2 cables 1) Lightning 2) HDMI
To understand more clearly, kindly find the attachment of Connecting an iOS port;