ESP stands for electronic stability program, which is one of the most widely used names for a safety feature that’s also marketed under other names, most of which include the word “stability,” such as electronic stability control, dynamic stability control, vehicle stability assist, vehicle stability control and StabiliTrak.
What ESP Does
ESP and its namesakes use antilock brakes under computer control to keep a vehicle on the intended course. It’s been required on all new U.S. passenger vehicles (below a 10,000-pounds gross vehicle weight rating) since the 2012 model year.
What ESP Is Not
ESP relies on two older technologies: traction control and an antilock braking system. Unlike ESP, those two are universal names that always mean the same thing, though their effectiveness naturally varies. The earliest, ABS, maintains traction and allows steering during panic braking by preventing lockup. Traction control helps a vehicle’s drive wheels maintain traction during acceleration.
How ESP Works
Piggybacking on the wheel-speed sensors and computer-actuated braking of ABS, stability systems add accelerometers and yaw sensors that can detect when the vehicle is spinning or sliding laterally. The computer constantly compares the vehicle’s motion to the position of the steering wheel to intuit if the car isn’t doing what the driver intends. If ever the two are not in synch, the computer applies antilock braking to any of the wheels in an attempt to keep the vehicle on course. (Anyone who has felt the car pull to one side during braking, which indicates that a brake job is needed, knows how disproportionate braking among the car's wheels can steer the vehicle.) The system works on anything from a rain-slick road to a high-speed racetrack.
At their worst, early examples of stability control could be a bit abrupt and intrusive, but they’ve always been effective and, at their best, are nothing short of astounding, which is why their inclusion became mandated despite the added cost. No stability system can break the laws of physics, change the dynamics of the vehicle itself or make up for plain old bad driving.
How to Use the Electronic Stability Program
Sometimes there are advantages to turning off traction control, especially in older cars where it can hinder acceleration too much in certain low-traction conditions, but there’s seldom a reason to turn off a stability system. Some cars don’t even allow it. Typically, owners can turn off traction control by pushing the stability control button briefly. In cars that allow it, holding the same button down for several seconds may turn off the stability function as well.