If you've experienced lane-keep assist in most vehicles, you know that such systems generally serve their purpose — keeping you from wandering out of your lane. But you may also know they tend to do so at a high cost, as they're often incredibly annoying. A recent Insurance Institute For Highway Safety study found that nearly half of all drivers actually turned off their car's lane-departure warning systems out of frustration. The study paints a ready illustration of how the best-intentioned active safety features can be poorly executed.
Fortunately, if my first test of Nissan's forthcoming ProPilot Assist system is any indication, you won't soon be reaching for its off button.
I sampled a prototype PPA system fitted to athis week, and found it to be both remarkably effective and unobtrusive. And I wasn't testing it on some cordoned-off test track or an arrow-straight stretch of freeway, either. Nissan plunked me down on Interstate 696 in suburban Detroit, in live, dense traffic, complete with MDOT's typically indifferent levels of road maintenance, including impressive mosaics of hot patch and faded lane markings.
PPA is a simple two-step affair. Thumb the blue button on the right steering wheel stalk, and the system is enabled. To activate, press the "SET -" button adjacent to it, just as you would for cruise control. Once a chime indicates the system is active, you can then use the +/- buttons to raise or lower your preferred speed, and the car will accelerate to -- and hold that speed -- whenever traffic conditions allow for it. (You can also adjust the following distance to the vehicle ahead using another button, but you probably won't feel the need to do that more than once).
Set to arrive on thethis fall and spread rapidly across Nissan's lineup thereafter, ProPilot Assist leverages forward-facing radar and a front camera mounted atop the windshield to read highway lane markings and scan the road ahead. When active, the system works to keep the vehicle in-lane and at a safe distance from vehicles ahead using the accelerator, brakes and steering system.
Most importantly, PPA isn't hardware that allows the vehicle to ping-pong disconcertingly back and forth between the white lines, it keeps you locked in and dead-center at all times, only allowing for a very slight drift from the middle in freeway bends to allow for cornering G-forces and help the car's motions feel more natural.
PPA will only activate under certain conditions — namely, it needs to detect that you're on a highway with usable lane markings. While ProPilot Assist does work from zero to 90 mph, it's not intended for city use. Nor is Nissan pretending that this hardware suddenly affords autonomous running -- on the contrary, "Assist" is in the system's name for a reason -- PPA is a hands-on, Level 2 system designed to reduce driver stress and improve safety.
It's worth noting that I didn't get a chance to test PPA where it will probably be the most useful -- in rush hour's stop-and-go slog. The system should allow for significantly fewer freeway-commute headaches, enabling it to crawl along safely in traffic jams, automatically matching the pace of traffic, right down to a halt.
If the flow comes to a standstill for more than three seconds, the driver will need to manually reactivate PPA, either by thumbing the resume button on the steering wheel or, more intuitively, tapping the accelerator. Presumably, the system could be programmed to resume on its own after longer intervals, but the 3-second timer is a subtle way of keeping the driver aware and engaged.
How else will PPA keep the driver alert and on-task? Like other systems, there's a sensor to detect torque inputs to the steering wheel, which could be anything from a driver's minor steering correction to a lane change. Basically, the car knows your hands are on the wheel because you're constantly making minor to major steering movements, whether you're really cognizant of them or not.
Take your hands off the wheel, and the system goes through an appropriate progression that effectively starts as a gentle tap on the shoulder and eventually graduates to full-blown freakout. It begins with a warning in the gauge cluster, which increases its urgency after a few seconds and is joined by a specific alert tone. If you still don't get with the program, the car taps its brakes twice in quick succession to jolt you back into awareness. If you're still out to lunch, PPA essentially assumes you've been incapacitated, triggers the hazard lights, and slows you to a stop in lane.
Of course, it would likely be safer to have the system signal a lane change and steer the vehicle safely to the shoulder and stop, but even the— which is claiming to be the world's first Level 3 production car — follows the same course of action. Doing so would likely require more mechanical redundancies, which would add cost and complexity. Either way, the driver always has the option to override the steering, braking or acceleration at any time.
For the moment, at least, ProPilot Assist is a single-lane system — it won't automatically signal and steer you into an adjacent, freer-flowing lane when the opportunity presents. As the driver, you can, of course, choose to initiate a lane change — using a turn signal or otherwise — by steering the wheel as normal. In my experience, the system never fights you when doing this, and it automatically reactivates once in the new lane.
What's the biggest takeaway impression from my prototype tech drive? Not only does ProPilot Assist seem to work well, it's actually pleasant and remarkably natural-feeling to use -- it doesn't make the wheel feel overly busy or nervous, nor does the weighting feel wonky. It's worth noting that those are impressions coming from someone historically averse to such systems. Oh, yes. Full disclosure: I am one of those drivers who quite regularly turns off lane-keep assist systems in the new cars I test. I dutifully try them out for a few days, of course, but if I find them cumbersome or unpleasant, off they go. (That used to be true of blind-spot monitors, too, but they have improved so much that I now rarely turn them off.)
In terms of hardware, this is actually a pretty simple system. But at first blush, and as the first step on the road to full self-driving capability, ProPilot comes across as very smartly executed. There are a number of automakers that already offer similar technology, but it's typically featured on much costlier luxury cars. Nissan hasn't priced ProPilot Assist yet, but after it debuts on the Leaf, it's expected to become available in short order on many of the company's higher-volume, lower cost vehicles -- models like the Rogue seen here. Based on my first impressions, that's good news — both for Nissan buyers and for the motorists who share the road with them.