The other companies who will want this technology (car companies) are extremely well connected politically, and infinitely more experienced than Google at lobbying (see gas mileage requirements).
Google simply won't be allowed to monopolize the technology, no matter what patents they have.
Seems like they are looking for partnerships (they wouldn't really want to get into the business of integrating and building the whole hardware I expect):
> While Google had no immediate plans to commercially develop the system, the company hopes to develop a business which would market the system and the data behind it to automobile manufacturers (from the Wikipedia page).
Google simply won't be allowed to monopolize the technology, no matter what patents they have.