Thoughts on BLIS

I purchased my V60 in Hartford, CT. If you've ever been there, you've probably experienced the joys of its highway system. Connecticut drivers are prone to dallying in the left lane even at baseline, but I-84 through Hartford accentuates this highly annoying tendency by employing a large number of left exits. To make things worse, I-84 curves through the city, and drivers seem to stomp on their brakes whenever they sense even the tiniest bit of lateral g-force. The result? About 7 miles of absolute fucking chaos.

I've always tended to pooh-pooh driver aids. My Honda Fit didn't even have traction control (and with 109 raging horsepower, maybe it didn't need it) and my Ford Focus ST had traction control but nothing else. In spite of my grumpy-old-man attitude, I immediately appreciated the extra security blanket afforded by Volvo's blind spot monitoring system (BLIS) as I drove away from the dealership. It works extremely well when cars are approaching from the left or right, giving you a subtle amber light in the corresponding A-pillar. If you flip on your turn signal as if you're about the change lanes into the car alongside you, the light changes from solid to blinking. It doesn't beep, unlike Mercedes and some other manufacturers' systems, and I appreciate the subtlety.

So BLIS works very well when a car is approaching you. However, it doesn't work well when you are passing others. As you pass and a car transitions into your blind spot, the system will light up about 75% of the time. The other 25% of the time the system does not react. It appears that this behavior might be related to closing speed - it seems that if I approach a car slowly, BLIS will activate, but if I'm passing more quickly, it is less likely to do so. There is some inconsistency and I've been unable to determine if a specific closing speed will or won't activate the system.

Here's an example of BLIS working properly (the blinking is due to the camera - the light is actually constant):

And here's an example of BLIS failing to light up:

I don't think this is a deal breaker. Presumably when you're overtaking, you are already aware that the car is in your blind spot. Volvo's manual itself states that the goals of BLIS are to react when:

• the vehicle is overtaken by other vehicles
• another vehicle is quickly approaching the vehicle.

The manual mentions nothing about when you are overtaking another car. I personally find BLIS to be quite helpful. Yet, this illustrates why manufacturers need to be very explicit and clear when explaining the function and limitations of driver aids. Volvo does a good job of explaining the limitations of City Safety in its manual but is far less detailed in its explanation of BLIS.

If you're in the market for a Volvo V60 or S60, should you get BLIS? I'd recommend it. You should be aware that driver aids can occasionally behave unpredictably, and you need to fight the urge to become complacent. Nevertheless, I find it reassuring to have a helpful yet unobtrusive safety system in congested, chaotic places like Hartford, Boston, New York, or other urban areas.

For further reading, check out this old but great article in Wired about the benefits and pitfalls of driver aid systems.