Years ago, whenever I went on long fishing trips with my friend Chris, we had a rule for the drive home—nobody gets to sleep. At the end of a long day, we wanted all eyes scanning the road for hazards. Sure enough, one day I spotted a big deer springing onto the highway, and my warning cry gave Chris, at the wheel, the extra split second he needed to avoid it.

Close call.

The Advanced Pre-Collision System (APCS) with Collision Avoidance Assist[1], available with the new 2013 LS, is kind of like having an alert buddy with you—except of course, this buddy is equipped with super-sophisticated things like millimeter radar and near-infrared rays.

In short, it’s one of the most advanced automotive safety systems available.

We’ve talked about Lexus Pre-Collision and Advanced Pre-Collision systems before, available in the previous generation LS and other models. But this latest Advanced Pre-Collision System with Collision Avoidance Assist is designed to do some cool new stuff.

But before we get into that, here’s a quick APCS primer.


In a nutshell, when activated, APCS constantly scans for hazards ahead while the vehicle is in motion. It does this using milliwave radar, which is emitted from behind the Lexus badge, plus a stereo camera that’s integrated into the rear-view mirror.

The system scans beyond the range of the low-beam headlights, meaning the APCS-equipped Lexus models have the potential to recognize a hazard at night before a fully alert driver can see it.

And while APCS is scanning the road ahead, another system, the optional Driver Attention Monitor, is monitoring the direction the driver is facing to confirm that you’re facing forward. (New to the 2013 LS, the Driver Attention Monitor also monitors your eyelids.)

In the event of a hazard in your path, a whole lot of different things happen very fast. Right away, the APCS computer calculates the LS’s speed and closing ratio. Meanwhile, the Driver Attention Monitor is calculating the driver’s status: Are your eyes fully open? Have you turned to face your buddy to reemphasize the size of that huge rainbow trout you caught earlier?

In both situations, the system will flash a warning light and sound an alarm; if that doesn’t get your attention, the Collision Avoidance System is designed to actually apply the brakes.


The purpose of applying the brakes is two-fold: to get the driver’s attention so that further evasive action can hopefully be taken, and also to help mitigate the effects of a potential collision. As part of its capabilities, this newly available APCS feature is designed to bring the 2013 LS to a complete stop at speeds below 24 miles per hour.

Another enhancement for the 2013 LS is that the system not only recognizes other vehicles but pedestrians as well, thanks to two stereo cameras facing outward. It’s also noteworthy that the system works day or night—many similar systems in non-Lexus vehicles are designed only for daytime operation.


So about those worst-case scenarios, where the vehicle is really, really coming up on something, and a collision is unavoidable?

Here, the passive safety features of the Advanced Pre-Collision System come into play. To help give the driver an added advantage, APCS pressurizes the Brake Assist, so that once the driver applies the brake, it will deliver extra braking power.

Also, to help protect the driver and front passenger, when APCS detects that an unavoidable frontal collision is imminent, it retracts the front seatbelts. On vehicles equipped with Adaptive Variable Suspension or Air Suspension, it also stiffens the front suspension to help prevent a nose dive from sudden braking, which in turn helps the driver keep control.