I would definitely watch yourself when trying to tie into the iDrive system. This is why INViSiON builds their products "Stand alone". The BMW iDrive Telemetry is extremely sensitive!

If I walked into an aftermarket location they would probably tell me the same thing. Yes the aftermarket location can do it but how well does it work is what you should be asking them and also show me on another customer's car or show me a demo before they slice in and you get an "OOPS!" At least get a reference or testimonial.

There are several companies that make interfaces for other BMW models that would allow any video source (including a NAV system) to be displayed on the iDrive screen. However, I don't know of any so far that would allow you to use the iDrive knob to actually control the aftermarket devices such as the NAV system. Even iPod interfaces have to "pretend" that the iPod is the CD changer to be able to interface with and be controlled by the iDrive system, this includes both aftermarket AND BMW's own OEM iPod interface. BMW's USB factory installed interface does not have this limitation, but even BMW could not come up with a post production or dealer installed iPod interface that could be fully integrated and controlled by iDrive without pretending that it's the CD changer.......so I doubt that the system that they are quoting you is in fact integrated in iDrive and controlled by the iDrive knob. Most likely they are just installing an A/V switcher that has its output interfaced with the iDrive's LCD screen and it just simply allows all the different video sources (including iDrive, NAV system, and DVD player) to share the LCD monitor and plays back the audio using the car's audio system. In this scenario when you want to use the NAV you would switch the input to NAV and would see the NAV info displayed on the iDrive screen, but you would still have to use the NAV system's controller to access it, not the iDrive knob. When you want to use the iDrive again you would have to switch the input back to iDrive in order to see it displayed on the screen.

I would never get an aftermarket NAV, even if it did have better features than the BMW one because I like the integration of the OEM system. I would still love to find out the details about what they actually mean when they say their system "works" with iDrive cars. Do they mean that it truly integrates with iDrive and can be controlled with the iDrive knob, or is it simply using iDrive's LCD screen to show the NAV information? I suspect it's the latter case.