An illustration of how Blind Spot Warning systems work.
Illustration: John Ritter

Blind spot warning (BSW) systems use cameras, radar, and/or ultrasonic sensors alongside your vehicle to detect vehicles you can’t see that are next to or behind your car. If a vehicle is detected there, drivers get a visual warning, often in the outboard mirrors, or on the front pillars. When drivers activate the turn signal, some BSW systems give an audible and/or tactile (shaking steering wheel, for example) alert to indicate that it’s unsafe to merge or change lanes.

These systems come in two varieties:

Blind Spot Warning (BSW): Drivers get an audible and/or visual alert that there’s a vehicle in their blind spot. The system may provide an additional warning if the turn signal is activated when it is unsafe to merge or change lanes.

Blind Spot Warning With Automatic Emergency Steering (BSW w/AES): The system automatically steers and/or brakes when the turn signal is activated during a lane change maneuver and a vehicle is occupying the blind spot in an adjacent lane.

In a most recent survey, we asked CR members to rate their experiences with the advanced safety and driver-assist systems on their model-year 2015-2019 cars. Respondents answered questions about their satisfaction with the systems and told us which ones helped them avoid a crash. The survey covered about 72,000 vehicles. See the highlights below.

Which Brands Do BSW Best?

Most satisfying systems, according to CR members: Genesis, Jeep, Lexus
A Genesis owner from New York sang praises for BSW, writing, “This is the single most valuable technology ever invented. It has saved me and my wife from numerous accidents, and we would never buy another car without it!” Explaining how it helped them, a Subaru owner said, “It saved me from sideswiping a car that had just changed lanes before I was changing lanes to pass a car on the interstate during my initial test drive.”

Least satisfying: BMW, Volkswagen, Tesla
One BMW owner points out the limitations with some systems, writing, “It actually turns off if my speed drops below 30 mph. What were they thinking? In bumper to bumper traffic it doesn't work! Or [in] slow moving traffic. Plus the light isn't in the mirror so it's not immediately apparent if the light is on. Also hard to see if it's too sunny.” A Tesla driver reveals a factor with some blind spot warnings—the location of the warning: “The blind spot monitoring system only displays on the center display panel, which is out of the line of sight of a driver using any rearview mirror during lane changes.”

CR’s Take: BSW is one of CR’s recommended safety features. CR gives bonus points to models that have it as standard equipment across all trims, and our members also rate it favorably. It makes for safer lane changes, a real boon for drivers in vehicles with big blind spots. CR’s testers prefer systems that use a bright warning light on the side mirror, as opposed to on the infotainment display screen or instrument cluster. Even if shoppers have to pay extra for this feature, we don’t think they’ll regret it.  

Blind Spot Warning
Do owners like it?
Say the system helped them avoid a crash
Trust the system to work every time
Source: Consumer Reports' Advanced Safety Systems Survey.

Brand Names for Blind Spot Warning

AcuraBlind spot information
Alfa RomeoBlind spot detection
AudiAudi side assist
BMWBlind spot detection
BMWActive blind spot detection
BuickSide blind zone alert
CadillacSide blind zone alert
ChevroletSide blind zone alert
ChryslerBlind spot monitoring
FiatBlind spot monitoring
FordBlind spot information system (BLIS)
GenesisBlind spot detection
GMCSide blind zone alert
HondaBlind spot information
HondaBlind spot monitoring
HyundaiBlind spot collision warning
HyundaiBlind-Spot Collision Avoidance Assist
InfinitiBlind spot warning
JeepBlind spot monitoring
KiaBlind spot collision warning (BCW)
LexusBlind spot monitor
LincolnBlind spot information system
MazdaBlind spot monitoring
MazdaRear vehicle monitoring system
MazdaAdvanced blind spot monitoring
Mercedes-BenzBlind spot assist
Mercedes-BenzActive blind spot assist
MiniBlind spot detection system
MitsubishiBlind spot warning
NissanBlind spot warning
PorscheLane change assist
SubaruBlind spot detection
ToyotaBlind spot monitor
VolkswagenBlind spot monitor
VolvoBlind spot information

Guide to Advanced Safety Systems

We tell you which safety systems owners like, and the brands that do them best.