Google surprised us all this week with news that the company has been secretly testing autonomous cars for years. The project isn't exactly new: Google's fleet of self-driving Toyota Priuses have already logged 140,000 miles driving across California using cameras, radars, and lasers. Sebastian Thrun, creator of Google's Street View and the director of the Stanford Artificial Intelligence Laboratory, has been building autonomous vehicles since 2005. And Thrun isn't the only one.

The EUREKA Prometheus Project, launched in 1987 by Daimler-Benz AG, was the biggest research and development project ever in driverless cars, garnering today's equivalent of one billion dollars in funding from the European Commission. In 1994, twin robot vehicles VaMP and VITA-2 drove over 600 miles on a Paris highway in standard traffic conditions. The program ended in 1995. Maybe the project's acronym was partly to blame: Prometheus was short for 'PROgraMme for a European Traffic of Highest Efficiency and Unprecedented Safety.'

In the mid 1980's, DARPA's Autonomous Land Vehicle (ALV) successfully completed the first road demonstration using laser radar. In 1987, the vehicle showed off the first off-road map and sensor-based autonomous navigation system, traveling across terrain containing slopes, ravines, and rocks, among other obstacles.

The Argo Project, a driverless car program that began at the University of Parma in 1996, saw the MilleMiglia in Automatico ARGO car drive itself 1,211 miles autonomously on Italian highways. The car used stereoscopic vision algorithms for navigation.

DARPA's Grand Challenge, which launched in 2004, was the first long distance competition for driverless cars. Over 100 teams registered during the competition's first year. The first year saw DARPA offer $1 million to Carnegie Mellon's Red Team, while the second year's grand prize was $2 million (Stanford Racing Team took the prize).

DARPA's Urban Challenge, a spin-off of the Grand Challenge, featured a 60 mile race on a closed course in Victorville, Ca., that had to be completed in under six hours. Tartan Racing, a collaboration between GM and Carnegie Mellon University, took the $2 million first prize.

The VisLab Intercontinental Autonomous Challenge, another University of Parma project that was launched in 2010, sent two electric autonomous vehicles on the road from Parma, Italy to Shanghai, China. The cars are still on their journey today.

The Junior autonomous car, a collaboration between Volkswagen and Stanford researchers, was a competitor in the DARPA Urban Challenge. Since then, two more iterations of Junior have been built. The latest, Junior 3, can cruise down a driveway and back into a tight parking space.

GM's EN-V road-connected autonomous car features vehicle-to-vehicle communications, distance-sensing, and GPS. At the same time, real-time traffic information can be leveraged to automatically select the fastest route to a destination. The EN-V is just a concept platform for now, but GM has said in the past that it expects to start testing driverless vehicles by 2015.