iPhone 3G, '07 (July) , USB Interface

[Ferguson]

I've been searching web sites for a couple days with mixed results.

'07 X5 with USB/Ipod interface, 3G Iphone, wife has an iPod.

If I plug the iPod into the USB with JUST a vanilla Apple USB cable, it is recognized and I can control it with the idrive interface.

If I plug the iPhone 3G in with just the USB cable it charges, but no music, no control ("USB" is grey on the idrive and cannot be selected).

I'm using a real Apple USB cable. And note the 3G does charge.

I do not have a "Y" cable. It sounds like I was supposed to get one with the car, I do not think I did. Even if I did, I understand that the '07 cables do not work (will not charge) the 3G, a post-August-08 cable is needed. Local dealer did not have one (though I could order, haven't yet).

It's not clear why I need the Y cable to work with the iPhone when the iPod works just fine without? Which makes me hesitant to go lay out $70 for a Y cable at the dealer (dealer who said "I can't guarentee it will work" by the way). I worry I will get it, plug it in, and nothing but AUX (non-USB) will work. Not what I want.

If the USB cable alone works on an iPod should I expect to need the Y cable for the iPhone?

$70 for just a cable?

And what a disappointment that the fancy tray for the iPhone ONLY does antenna and power, not integration for music control.

PS. So far the blue tooth integration is working fine, a few quirks I may put separately.