During the second day of Formula 1's winter testing in Barcelona, engineers were spotted huddling around screens to watch footage of Lewis Hamilton doing something peculiar in his Mercedes-AMG W11.
In addition to turning his steering wheel like any normal car, the six-time F1 champion could be seen tugging the wheel toward him and pushing it away again along the straights. While that might sound like a mechanical issue, astute observers noticed that despite Hamilton keeping the steering straight, the front tires turned themselves ever so slightly toward or away from each other.
It wasn't long before we found out that it wasn't a mechanical issue, but something Mercedes-AMG calls Dual Axis Steering, or DAS.
What you see Hamilton doing on that video is adjusting the car's "toe"--the alignment setting for how many degrees left or right from the center a wheel points--on the front tires of his Mercedes while the car is moving. By pulling the wheel toward him on the straight, Hamilton reduces his W11's toe-out, which is normally dialed in to trade mid-corner grip for turn-in grip. A reduced toe setting can reduce tire wear while also reducing rolling resistance, which also helps improve efficiency and top speed. Hamilton undoes the change before entering the corner by pushing the wheel back in again.
Why does Mercedes think it's necessary to do this? While there's no official word on what the team wants from DAS, it most likely has to do with being in control (much like everything else in F1). Being able to adjust the toe setting on the fly means a driver can remain in control of the handling characteristics of the car during the race. In our experience behind the wheel of non-F1 race cars, having the toe setting dialed in can help you waltz beautifully through the corners or make you look like it's your first day behind the wheel of a car. It can hugely affect the car's behavior because it dictates how the tires, chassis, and suspension will behave while the car is traveling in a straight line or turning.
In testing, Hamilton appears to use his new party-mode steering every lap, but the truth is that during the race he may only use it when needed. When could that be? Perhaps help with cold tires after a pit stop, maybe while trying to set the fastest lap of the race, or when degrading tires upset the driver's idea of the optimum balance. For all we know, it could be a contingency that's in place for an extremely specific scenario. On the other hand, if Mercedes finds it extremely useful in terms of performance--whether it be from a handling, tire, or time-savings perspective--it may become something as ordinary as pushing the drag reduction system (DRS) button every single lap.