It's only a matter of time before expensive in-dash navigation systems give way to much cheaper and even free smartphone nav apps, and the transition probably won't even move for Gen Y to get behind the wheel in droves — if they ever do.

Google blatantly makes the case for the death of in-dash nav in a new commercial for its Nexus S smartphone with latest version of Google Maps for Mobile 5.0. And shows that using the app is child's play — as long as you're sitting in the passenger seat.

The commercial depicts a kid riding shotgun with the Nexus S, giving his papa in the driver's seat directions from the phone's nav app. The driver then reaches over to turn off the in-dash nav system in what appears to be a Ford vehicle.

While the free Google Maps Navigation app on the Nexus S does offer a lot that most in-dash nav system can't — including accurate voice activation, Street View, and Internet-connected POI search — what it doesn't show is all the other infotainment content the driver looses by switching off the in-dash screen: audio, Bluetooth hands-free, back-up camera and a much better view than on a smartphone's small screen.

Maybe the next commercial of this type will come from Nokia, showing how its free Ovi Maps nav app can be integrated into a car — and transferred to an in-dash screen via a technology the auto industry is getting behind called Terminal Mode. Regardless, the commercial makes clear that the death knell for in-dash nav is drawing near.