What STI considers to be a ‘car that drives well’
Subaru’s works-based tuner, STI, has long been consistently proposing a “car that makes driving better”. This means that it is important for the car to move linearly and without time lag from operation.
The key is to make the inner wheels usable with minute steering
If there is a time lag between when the driver turns the steering wheel and when the car reacts, the driver will unconsciously turn the steering wheel more and more. When the car starts to react, the steering angle is large and the car rolls at once. This causes a large rolling movement, which is unstable. Passengers are also likely to feel uncomfortable.
At the same time, a slow response to the operation makes the driver feel uneasy. Just as you would break out in a cold sweat if you turn the steering wheel on a snow-covered road and the car goes straight ahead, so too does a delayed response to controls lead to a sense of fear.
In other words, reducing the time lag between maneuvers and ensuring that the car moves linearly can eliminate a sense of unease. It also prevents the steering wheel from being turned too far, allowing the car to turn in a stable and natural posture. In other words, the driver can feel that they are driving better.
To achieve this, it is important not to mistake the meaning of linear. Linear means that the car responds promptly to the controls, which is different from being overly sensitive to the controls.
STI particularly focused on the use of the inner ring this time. In particular, the use of the inner ring when the steering wheel starts to turn. When a car is about to turn, the load is applied to the outer wheels by centrifugal force. However, if you rely only on the outer wheels, the limit becomes low and only the outer wheels are crushed, resulting in jerky movement.
Therefore, the inner wheel moves ahead of the outer wheel, enabling smooth cornering.
The force of the inner wheel only occurs for a moment. The uniformity of body rigidity is important for how that moment can be used. If the rigidity of the entire body is well balanced, the inner wheels can be used to start the turn, and the car’s response to minute steering angles will be better.
