Volvo's Pilot Assist II in the 2017 S90 combines adaptive cruise control and lane-keeping assist for semi-autonomous driving. Fully autonomous cars are coming, but concerns ranging from regulatory issues to the handoff between machines and humans need to be addressed before drivers can let go of the wheel – and trust the technology. In the meantime, we'll likely be stuck in a middle ground of semi-autonomy between Level 2 and Level 3 over the next few years. Systems such as Tesla Autopilot, Mercedes-Benz Steering Assist and Volvo Pilot Assist II can take over part if not most of the driving task but still require human supervision – and a certain level of trust on the part of the driver. In the case of the Mercedes Steering Assist and Volvo Pilot Assist II, occasional driver intervention is required, otherwise the system deactivates.

An Audi A8 in testing mode works on refining a suite of semi-autonomous driver-assist features that allow drivers to hand over some tasks to the automobile, though they must check in with the steering wheel often to keep the system active. Car companies battling for their share of $2 trillion in annual global auto sales increasingly lean on shiny tech that takes over some of the driving from humans. Boasting names such as Autopilot, Super Cruise and ProPilot Assist, these systems -- whose radar and cameras are the building blocks of self-driving cars -- are part of a growing effort by manufacturers to woo with computing power rather than horsepower. But on the heels of two Teslas that crashed while on Autopilot, automakers find themselves increasingly torn between hyping the tech and warning owners about its limitations. Nissan's ProPILOT Assist technology, which is paving the way for future fully autonomous vehicles, is aimed at reducing the hassle of stop-and-go driving by helping control acceleration, braking and steering during single-lane highway driving.

How on earth did they get their driver's license? This is something we've all said about some maniac on the road. Despite strict laws, there are still plenty of people not concentrating on the road. Thankfully, the future of safer driving is upon us. The eventuality is that driving could become a thing of the past.

With one eye on the road and another on a tiny green steering wheel icon emblazoned on the display in front of me, I watched as the all-new 2017 Mercedes-Benz E-Class drifted across the yellow lane marker. Just as the lefthand tires crested the line, the car proceeded to buzz the steering wheel to warn me, the driver, of an unsignaled lane departure. "Oh, don't give me that," I hollered at the car, as I grabbed the wheel and jerked the mid-size luxury sedan back into the lane. Now back in my lane with the Mercedes mostly keeping itself in check, my heart sank a bit. I felt disheartened because Mercedes' new suite of semi-autonomous safety tech, Drive Pilot, simply didn't feel as robust as Tesla's Autopilot that I had tested on the very same stretch of freeways some eight months before.

Just three years ago, autonomous cars seemed like a pipe dream relegated to a far-off decade in the future. But then, last week, Ford announced that in 2021 it's planning to release an autonomous car without a steering wheel, brake or throttle pedals, designed for ride-sharing. Just a few days later, Volvo and Uber made public their partnership to develop a driverless car. Now, it seems autonomous cars aren't just a fanciful future prospect but rather something tangible -- and a real part of mobility in the near future. The Ford and Volvo/Uber announcements, though, highlight the different approaches each company working on autonomous driving technology is taking. For example, some, like Audi, are introducing autonomous systems slowly into their products to indoctrinate their buyers to the tech. Others, like Ford, are jumping straight to driverless cars.