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The self-driving car market is beginning to rev up. Japanese car maker Toyota on Tuesday announced that it planned to have self-driving cars commercially available by 2020 -- the same year Nissan, General Motors and Google plan to have autonomous vehicles on the road.

Toyota revealed that it has been testing its self-driving technology with a car called the Highway Teammate, a modified Lexus GS that's been cruising around Tokyo's busy Shuto Expressway. It has safely and successfully been changing lanes and merging into or exiting out of highways, all completely autonomously.

The Japanese automotive manufacturer is branding its self-driving technology the Mobility Teammate Concept. "Interactions between drivers and cars should mirror those between close friends who share a common purpose," the company said in a statement, "sometimes watching over each other and sometimes helping each other out."

A good deal of noise has emerged from the prospective autonomous car market this year. Google, after many years of testing out the technology, revealed its intentions to release smart automobiles for sale in the next five years. There have been rumours that iPhone maker Apple hopes to enter the car market in 2019, with The Wall Street Journal reporting recently that the Cupertino, California-based company is readying an electronic, partially-self-driving vehicle.

It's not only tech companies -- automakers old and new are developing self-driving cars too. Nissan has also pegged 2020 as the year it releases its first autonomous vehicle, while Telsa CEO Elon Musk said on Tuesday at the Vanity Fair Summit that self-driving cars are "two or three years away."

Tuesday's announcement comes after Toyota invested $50 million (AU$69 million or £33 million) in artificial intelligence research in the hopes, it said, of making driving safer. The money will be be split between Stanford University and the Massachusetts Institute of Technology (MIT), which will build two joint research centres.

The company is expected to reveal more details of its self-driving cars at the Tokyo Motor Show, which opens its doors on October 29.