In the world of autonomous driving, no manufacturer has pushed its road-legal technology further than Tesla. Under the right conditions, Autopilot will accelerate, brake and steer for the driver, provided you've got your hands on the wheel. New Atlas hit the road in a Model S P90D to test the system out.

Autopilot uses a vast army of sensors and cameras to guide the car. Up front, there's a radar unit and a camera to read the lines on the road. These work with 12 long-range ultrasonic sensors that project 16 ft (4.8 m) in every direction around the car, in order to build a clear picture of what's sitting beside and behind you at any speed.

The thought of all this technology working behind the scenes, with no way for the driver to know what's going on is slightly unnerving. Tesla has looked to provide some peace of mind through the instrument cluster, with the Model S' display having been updated to include an image of the car that gives an indication of what the car is seeing.

Cars in your lane show up as little Model S' on your screen, and there are small colorful lines that pop up around the edge of the car as obstacles start to creep into your car's personal space. It's reassuring to know that the Tesla sees that kerb that caught your eye, although watching the lines go from green, to orange and wondering whether the car will react serves as a good test of your nerve.

What does all of that mean? Well, here at Gizmag we went the extra mile to find out: we turned off our inner control freak, turned on Autopilot and let the car do the work for us.

As you'd expect, it's completely unnatural when the car takes control. The driver's display is quick to remind you to keep your hands on the wheel, but it's more of a legal requirement than anything else, because in most situations the Model S handles itself perfectly competently.

In fact, the system does such a good job it's almost boring. Sitting on the busy freeways around Melbourne, the gap between us and the car in front never changes. As the road sweeps left and right, the car's wheel gently turns with it – it's not perfectly smooth, and the car tends to wander around in the lane a little bit, almost as if it's searching for reference points to base its path on.

Every now and then the Model S is caught off guard by lane markings that don't quite fit the normal pattern. As solid white lines around the edge of the freeway fade to open up for exits, Tesla's system gets indecisive, halfway between exiting and keeping up with the flow of traffic.

It's no surprise, then, Tesla recommends drivers use the system in the middle lanes of the highway. It's also not surprising to know the driver needs to be ready to take control of the wheel at all times, just in case things go wrong.

The other big piece of technology in Tesla's Autopilot arsenal is the automatic lane change function, which means you don't have to take manual control to duck around slow traffic on the freeway. If the automatic steering and radar cruise is mundane, trying to change lanes using the system will certainly inject some excitement into your day.

Even in ideal conditions, cruising along in the middle lane of a well-marked highway with no other cars around, we couldn't get it to work consistently. If the virtual driver controlling the steering wheel and speed is like a slightly nervous middle-aged driver, they become more like a 15-year-old taking their first drive on the highway when changing lanes.

It will edge out to the white line and pull back, before darting sharply across to the next lane. Of all the scary moments caused by Autopilot, lane changes had our heart in our mouths the most.

Thankfully, it's easy to take control if the system makes a mistake or doesn't act as expected. If you touch the brakes or pull the wheel, the system cuts out straight away and logs what the driver did to correct the error.

Every time you need to manually take control details about what the driver did and where they did it are sent back to Tesla, where they're sent out to the rest of the Autopilot equipped cars on the road. Essentially, it means Tesla's cars shouldn't make the same mistake twice.

So, what does all of this mean in the grand scheme of things? After all, Google's cars are averaging between 10,000 and 15,000 miles (16,000 and 24,000 km) per week of autonomous driving and Tesla says its cars have data on every inch of road in California. With that much information gathering going on, it's incredible to think of what Autopilot will be able to do in 12, or even six months time.

For now though, it's more of an extension to the radar cruise control system. The future of autonomous cars is coming at a rapid rate – that we know – but Autopilot is just a stop on that journey at the moment rather than the final destination.

Check out video of the Autopilot road test below.

Product page: Tesla Motors

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