Formula 1 teams are facing an increasingly tough call on whether or not to pursue passive double DRS in 2013, despite rules tweaks that should theoretically boost its advantage.
The FIA has changed the DRS regulations for this year, with drivers now only allowed to activate the device in practice and qualifying at the areas of the track where it will be used in the race.
Trick 'double DRS' like those used by Mercedes and Red Bull - which fed air through ducts in the rear wing to help stall the aerodynamics for a straight line speed-boost - have also been outlawed.
However, passive DRS concepts as tested by Mercedes and Lotus last year, which can stall the wing for a speed boost on all straights, remain legal, and should produce a bigger advantage because of the rules tweak that restrict normal DRS usage.
Click here to read about how the passive DRS systems work
The implementation of the passive double DRS remains far from a no-brainer however, especially after both Mercedes and Lotus encountered difficulties in gaining confidence with the systems last year.
The biggest problem was in getting the device to switch on and switch off at the correct speed.
The device has to trigger at a speed that is higher than the fastest corner, so drivers do not encounter a sudden loss of downforce in the high-speed turns where they need it the most.
This means that the benefit from the passive systems is limited only to those sections of straights that are faster than the quickest corners, so it is not as much value at venues with a lot of quick turns.
The ideal stomping ground for passive DRS is tracks that feature long straights and only low speed corners.
There is also a further complication in that Lotus and Mercedes both found that due to air pressure characteristics surrounding an F1 car, the speed at which the passive DRS switched off to reengage the rear wing was not always the same as that where it switched on.
This meant that the trigger point had to be adjusted even higher to ensure that there was no risk of drivers not having rear downforce for corners immediately after long straights.
Speaking about the concept at the end of last year, Brawn said that if the passive DRS got the go-ahead then it would be unlikely to feature on the car at every race.
"Where it engages and where it re-engages are often not necessarily the same speed - as it can have some lag," he said, when asked by AUTOSPORT about the difficulties Mercedes had encountered.
"For some tracks it will not be worth it, you won't be able to get any substantial advantage out of it.
"You need tracks with a good series of low speed corners, as soon as you get high speed corners you can't afford for it to be operating and the threshold becomes very high and the advantage is very small."
Ahead of a season where it is expected that the F1 field will closer further up because of rules stability, any advantage is still keenly pursued though, which is why passive double DRS remains attractive.
Brawn added: "The advantage of that is that you can use it all the time. I don't think it will make a huge difference in qualifying when you can use the normal DRS, but with passive systems they are every lap.
"At the moment you can only use DRS when you are close to a car in front, but with passive systems you can use them all the time, which is why they are attractive."
Mercedes and Lotus headed into the winter determined to keep evaluating the passive double DRS concept, and AUTOSPORT understands that both teams are still evaluating the idea as they close in on completing their 2013 cars.
It is also likely that rival teams have put work in to trying to get the systems working.
However, Brawn was convinced that even if teams do get the passive DRS working properly in 2013 then it will not be a golden ticket for success.
"The performance gain is there, but it is not huge," he said. "It's not like F-duct was. It is something that is nice to have, but it is not going to be a game changer in terms of your competitiveness."
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