As crazy as it sounds, self-driving cars could be less than a decade away.

Nissan said last week that it would be selling "autonomous" cars by 2020, while General Motors also said it would be doing the same.

According to CBS News and National Highway Traffic Safety Administrator David Strickland, the cars will probably not simply drive on its own for an entire trip, but instead will need some assistance from a "co-pilot," something similar to the way pilots operate a flight on co-pilot.

"The car--no matter how automated--is not yet ready to be more than a co-pilot," Strickland said. "And every co-pilot needs a pilot. Before self-driving vehicles can roam our streets, we have to resolve some of the challenges."

CBS News also says that Nevada, Florida and California are the three states in the country with laws allowing these kinds of cars to be tested.

A recent poll by Kelly Blue Book has found that 53 percent of people said they would refuse to buy a self-driving car, while 18 percent said they would consider one if it were available now. These numbers could change once there is reassurance that self-driving cars are safe and reliable, but until then it makes sense for customers to remain wary.

With this said, some current cars have started to foreshadow the future of this kind of technology. The 2014 Mercedes-Benz S is able to brake and steer itself in some situations while some BMW, Lexus, and other cars have the ability to detect whether the car is nearing a crash and can automatically brake.