A small team of Google Inc. engineers and people of the business staff met several of the world's largest car makers to discuss partnerships to build self-driving cars in 2012.

In one of the meeting, both the sides were enthusiastic about the technology but it was soon clear that they would not be working together. They disagreed on almost every point from car capabilities and time needed to get it to the market etc.

As Google expands beyond the Web and seeks to create a mark in the automotive market, the company's eagerness has begun to reek of arrogance to some who see danger as well as promise in Silicon Valley.

Google's hopes of making autonomous cars a reality may finally require working with Detroit. The alternative is to spend billions of dollars to try to break into an industry in which it has no experience.

"The auto companies are watching Google closely and trying to understand what its intentions and ambitions are", said one person familiar with the auto industry.

"Automakers are not sure if Google is their friend or their enemy but they have a sneaking suspicion that whatever Google is going to do is going to cause upheaval in the industry".

Co-founder of Google Sergey Brin has described self-driving cars as an on-demand service that consumers summon when needed.

Global product development chief of General Motors Mark Reuss recently said that Google could become a "very serious competitive threat".

Self-driving cars can free people to do more things that earn Google money such as Web search.

Car makers such as GM, Volvo and Mercedes have been developing their own autonomous vehicle technology for years.

Another potential sticking point is the maps developed by Google which are essential for its robo-cars to operate, says Sven Strohband, a robotics expert who worked at Volkswagen until 2006 and was not involved in the discussions.