Nissan is releasing its Tesla Autopilot challenger in 2018 - here's what it's like to use

• Nissan will release its new ProPilot Assist feature in the 2018 Leaf.
• ProPilot Assist is a form of cruise control that will work in stop-and-go traffic. It will also keep the car in its lane when approaching curves.
• I tried the system out on a Nissan Rogue prototype and found it made driving in heavy traffic a far less stressful experience.

Nissan's electric Leaf is due for a big upgrade.

The Leaf will be revealed on September 6 and is expected to boast a range of 200 miles. Perhaps more importantly, it will be Nissan's first try at a Tesla Autopilot competitor. The 2018 model will feature the company's ProPilot Assist technology, a driver-assistance feature meant to take the stress out of highway driving.

As a level 2 system, Nissan designed ProPilot to handle stop-and-go traffic on highways, even in situations where it approaches a curve in the road. I tried the system out on a gray Nissan Rogue prototype that I drove along the Hudson Parkway for 45 minutes.

ProPilot Assist is powered by a front-forward radar, camera, and sensors. The system relies on clear lane markings to keep the car center on a highway.

I took the Rogue out on a rainy afternoon, which poses some challenges. Rain hurts the system's ability to detect the contrast between the lane markings and the road. For that reason, ProPilot Assist will not work in heavy rain when the windshield wipers are on their fastest setting.

Thankfully, it wasn't raining too much, so I switched the system on as soon as I merged onto the Hudson Parkway. It's a very easy system to use: simply tap the blue button on the steering wheel and set the desired speed. As expected, ProPilot Assist turned off whenever I hit the brake, but I could fire it up again by pressing the "res" button.

Whenever ProPilot Assist is turned on, it will first turn on Nissan's Intelligent Cruise Control system. That means the car can handle stop-and-go traffic but it will not try and steer itself. Steering Assist won't turn on until the car can detect lane markings, which can take a few seconds or minutes depending on the road.

Nissan's Intelligent Cruise Control is a dream. The brake is incredibly smooth. I approached a very irritating and heavy slow down near the George Washington Bridge and the car gracefully paused during each incessant stop-and-go scenario.

I was able to control the amount of space between me and the car ahead. I chose the least amount of space possible (as any respectable New Yorker should) and was pleasantly surprised to see the gap wasn't so large that cars were able to scam ahead of me. It also left enough space that I didn't feel like I was cutting it close, even during harsher stops.

As someone who regularly takes the Hudson Parkway to travel across the George Washington bridge, I'm upset I can't use Nissan's advanced cruise control in all future drives. I have yet to approach that area of the parkway without encountering a major slowdown. Letting the Rogue do all the work was the first time I've approached the bridge without feeling my blood pressure spike.

My experience with Steering Assist was less than ideal, but certainly not poor. When the feature is activated, a display in the instrument cluster will highlight the lanes in green. If it can no longer see the lane markers, it will turn off with a chime until it repositions itself again.

Steering Assist struggles in scenarios where lane markings are light or even different. I first turned on the system in the left lane, which had a solid-yellow lane marker on the left side and dotted-white lane markers on the right. Steering Assist was unable to detect the yellow lane for most of the test drive, which I was told had to do with the lack of contrast between it and the road.

The system definitely fared better in the center lane when the car was surrounded by dotted-white lane markers on either side. I wouldn't recommend using cruise control in the speed lane anyway, but it's worth noting that lane detection can be spotty.

When Steering Assist is activated, it handles gentle curves just fine. I could feel the car steer beneath my hands, which was unsettling at first but easy to get used to.

When I approached an aggressive curve, however, the car's natural instinct was to go flying forward unless I guided the wheel myself. It is not capable of handling sharp curves on its own.

Nissan notes that ProPilot Assist is not a self-driving feature, so drivers are supposed to help the car steer in these kinds of scenarios. But the feature felt a bit wonky and unsure unless the road was completely straight.

Generally speaking, I found using Steering Assist was more stressful than going without it. I constantly had to judge whether or not I should be heavy-handed when intervening or try to let the car work itself out before getting involved. I didn't enjoy that uncertainty.

Still, I will admit that I was using the feature in a difficult scenario. If I had been cruising down I-95's straight and wide-open roads, I imagine the system would have done just fine. I wouldn't bother turning it on while driving on a narrow or curvy highway like the Hudson Parkway.

Nissan is careful to ensure drivers don't mistake ProPilot Assist as a self-driving feature. If I let go of the wheel, a warning flashed in the instrument panel with accompanying warning chimes. Those chimes increased in frequency the longer I kept my hands off the wheel.

Nissan said if I had kept my hands off the wheel for roughly 30 seconds, the car would have gradually slowed to a stop. That seems like a much better solution than turning the car off altogether.

Overall, Nissan's ProPilot certainly takes the stress out of driving in heavy traffic. It's not a flawless system, but it's a welcome addition in a mass-market car. Nissan hasn't said how much it will cost, but a spokesperson told me it will be cheaper than Tesla's Autopilot system.

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