VEHICLE STABILITY ASSIST (VSA). It uses anti-lock braking system (ABS) technology, together with lateral acceleration sensors, wheel-speed sensors, steering position sensors and a dedicated microprocessor to detect wheel slip (understeer or oversteer). This helps the driver control the vehicle through a nearly instantaneous reduction in engine output (through the drive-by-wire throttle control) or the rapid pulsing application of one or more brakes as appropriate. For example, if the driver enters a corner too quickly and the vehicle's front wheels begin to slip (understeer), VSA almost instantly detects the situation and interprets it as understeer. VSA then reduces engine torque and selectively applies the brake on the inner front and rear wheels to help counter the understeer and enhance the driver's control. The correction happens so quickly and so seamlessly that the situation is often resolved before the driver is even aware of it.Another potential scenario involves a traction loss at the rear wheels, such as might be encountered when cornering on a dirty road or when encountering black ice. VSA detects the rear tires beginning to slip and quickly applies the outer front and rear brakes to counter the unwanted yawing motion and help restore control to the driver.VSA is armed automatically when the TSX starts. Any time the system is triggered, an instrument-panel-warning lamp alerts the driver that VSA is operating. The system can be switched off completely via an instrument-panel-mounted switch. The VSA system also handles traction control functions, enabling the vehicle to start and climb hills on low-friction surfaces with much greater ability and controllability. It utilizes ABS technology to sense wheel spin on the front (drive) wheels, and then implements individual brake application and drive-by-wire throttle control to restore traction. The benefit is greater security and active safety during winter snow driving or on other slippery surfaces including sand or water.

SH-AWD—What Does It Do?
There are many all-wheel-drive systems available in the U.S. market, however they are not all created equal. A typical all-wheel-drive system will feature a front and rear differential with a center differential that can direct power to the front or rear wheels, depending on where traction is needed.

While this is very effective for straight-line acceleration, it has limitations in cornering. To compensate for this, many AWD systems are teamed with traction control and stability control systems to provide yaw control. When the steering wheel angle doesn't match the actual direction of the vehicle, these systems can apply braking to individual wheels to turn the vehicle in the desired direction.

Acura's SH-AWD solves this problem with "torque vectoring." This means that not only can up to 70 percent of the power be directed to the front or rear wheels, power can be applied to individual rear wheels. When cornering, the outer rear wheel can be accelerated up to five percent faster than the front wheels with 100 percent of the rear torque going to that wheel. The result is similar to 4-wheel steering, in that the rear wheels help to point the car in the right direction on dry or slippery surfaces.