I wrote a post back in May on

The Mental Shift in the Collaboration Economy and Why it Matters to Everyone

The post is about how collaboration and sharing is taking off and specifically mentioned car sharing as a key example.

On Tuesday GigaOm had a notice up that GM was partnering with Relay Rides to allow users of OnStar to rent their cars out via a mobile app:

GM opens up OnStar with peer-to-peer car sharing service

This is the implementation of an announcement from back in October.

This is a big deal because it is about building services on top of existing installed technologies rather than people having to pay for new technologies.

It is also a big deal because OnStar has an installed user base of 6 million people which immediately gives the idea scale.

Our cars are one of our most expensive capital and operating budget items. In a time of financial uncertainty and risk a method which safely allows us to offset that cost by lending our car to a trusted social network may take off in a big way.

If that is the case then car makers better look out because they can throw out all their projections on future car sales.