I've added an info on adding vehicle image sets:

https://github.com/openvehicles/Open-Vehicle-Android/wiki/Adding-Vehicle-Ima...

Mark, maybe you can copy some of this to the iOS App wiki?

Regards, Michael

-- Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal Fon 02333 / 833 5735 * Handy 0176 / 206 989 26