Mercedes' DAS system: What is it? And is it a 2020 game-changer?

Hamilton shrugs off Verstappen's comments at Mercedes launch (1:24)

Lewis Hamilton speaks about Max Verstappen's comments as the 2020 Mercedes car is revealed fo the first time. (1:24)

This article was written in February, during Formula One's opening week of preseason testing at Barcelona's Circuit de Catalunya. Mercedes has since changed its livery to an all black scheme for the new season.

BARCELONA, Spain -- The biggest talking point from the first week of Formula One's preseason tests has been an innovative system designed by world champion Mercedes.

You might have heard about something called dual-axis steering, or DAS, over the past few days, as it has produced quite a buzz. Here's everything you need to know about it and why it has caused such a stir.

What is DAS?

DAS allows Mercedes' drivers to adjust the alignment of the front wheels from the cockpit -- something that was previously possible only when the car was stationary in the garage. The system is controlled by the driver either pulling or pushing the steering wheel, hence the name "dual-axis steering".

In testing, Mercedes appeared to have it configured to move the alignment of the wheels from toe-out (pointing slightly outwards when viewed from above) to neutral (running parallel). The drivers were seen activating DAS on the straights to bring the angle of the wheels inwards then returning it to its original toe-out setting for corners.

What benefits does it have?

Almost all setup options on a racing car are compromise solutions with positives and negatives, so by being able to switch between toe settings on track Mercedes can theoretically access the best of both worlds. The obvious benefit in the case of DAS is that Mercedes' new car, the W11, can run a relatively extreme toe-out setting for corners, which provides greater stability on turn-in, without the associated negatives that would come on the straights.

When running a toe-out setup on the straights, the tyre scrubs along the track surface due to its alignment and, combined with the camber setting (how much the tyre is angled inward when viewed from the front), it tends to heat up in the inner shoulder. Too much toe-out and the overheating can lead to physical damage to the tyres, such as blistering. But by using DAS to switch the toe angle to a more neutral position on the straight, the tyre will not be as prone to overheating on the inside shoulder, allowing Mercedes to run more extreme toe-out for cornering than it would not have normally got away with.

DAS also has the potential to help with tyre temperature management, giving Mercedes the option of scrubbing the tyre when it needs more heat in the rubber and bringing the toe angle in if it needs to reduce temperatures.

Is it legal?

Mercedes has been working on DAS for over a year and has been in touch with the FIA about its legality during that period. The fact it has made it onto the car at preseason testing suggests that there have been no major concerns over its safety and that the FIA has indicated that it is happy with DAS in terms of whether it complies with this year's regulations.

The key distinction appears to be whether DAS is viewed as a steering system or a suspension device. Parc fermé regulations prevent teams from making suspension setup changes from the moment the car leaves the pits for the first time in qualifying to the start of the race and are designed to stop teams having a qualifying-spec car and a race-spec car. Toe angle is included as part of the suspension settings the teams must lodge with the FIA before leaving the pits for qualifying and a change to that could be perceived to be against the regulations.

But Mercedes is treating DAS as a steering system, hence the name dual-axis steering, and considering it is operated via the W11's steering system, it is likely on solid ground. If Mercedes can successfully argue it is simply a steering function, then the team might be able to use it in qualifying, but if not, it should still be able to use it in the race.

Mercedes' main rival, Ferrari, has already confirmed that it will seek clarifications on DAS' legality, but that is likely to be more of a fact-finding mission than a precursor to a protest, and it would be surprising if other teams didn't do the same.

However, the 2021 regulations already appear to outlaw such a system under a new article that does not exist in the 2020 regulations. That suggests the FIA was aware of it, admitted there was a loophole this year but has opted to close it off for next year.

Will other teams copy it?

It is clear from the reaction of rival teams that DAS will not be an easy system to develop. Speaking on Friday, Ferrari team boss Mattia Binotto gave midseason as a rough estimate of when a copycat system could be ready and confirmed that it would not be possible to develop one in time for the opening races of 2020.

However, with teams already splitting time between this year and major regulation changes for 2021, there are limited resources to dedicate to such a project, especially if it will be of no use in 2021.

How big an advantage will it be?

This is the big question. Mercedes would not have developed it for over a year if it did not believe the system was worthwhile, but trying to put a number on it at this stage is almost impossible.

Mercedes itself is still trying to gain a full understanding of the benefits of DAS, and there's the potential that it's worth more at some tracks than others. However, no-one seems convinced it is a true game-changer, and other, less novel, developments on the Mercedes could well carry an even bigger performance advantage without attracting the same kind of media scrutiny. As is always the case in F1, the whole package has to work to win races.

Of course, you would rather have the flexibility that DAS offers than not, and each team will have to assess whether the advantage is enough to pursue a similar system for the second half of the year.