Formula 1 could be heading for more controversy surrounding double diffusers this season, amid predictions from leading teams that some of their rivals have pursued 'extreme' solutions in the area of car design.

With the opening rounds of the 2009 championship overshadowed by protests and an FIA appeal court hearing about the legality of the twin floor concept, there had been hopes that the subsequent clarity of the rules would help the sport avoid a repeat this time out.

However, amid suggestions that teams have exploited the rules even further, there are now fears that there could even be more protests in the weeks ahead.

McLaren engineering director Paddy Lowe said at the launch of his team's 2010 challenger on Friday that his team had pushed the diffuser regulations as far as it felt was possible.

"This is the first car in which we have had a clean sheet of paper to really exploit the interpretation [of diffusers] that was developed last year for a design of floors," said Lowe.

"You will see we have produced a fairly extreme incarnation of that but we won't be alone in that. We believe you will see some pretty extreme solutions on our competitors' cars as well."

The potential for these extreme solutions has led to Ferrari voicing fears that not every team is operating within the interpretation of the regulations that it feels is in place.

"We were and still are convinced that the double diffuser concept was illegal," Ferrari technical director Aldo Costa told Gazzetta dello Sport. "We feel there may still be interpretation over this, as the rules leave the door open to many possibilities. It's up to the FIA to supervise, but we are rather worried."

Piero Ferrari added: "I expect a Ferrari worthy of the title, unless someone interprets the rules differently."

Lowe is more confident, however, that the rules are clear enough - and that the matter will not require intervention from the FIA.

"We think the interpretation is very clear," he said. "In certain aspects we have sought guidance from the FIA and they have come out with very clear interpretation, understanding and guidance - and we think that has been made available to all the teams.

"We are hoping for a much cleaner start to the season then we had a year ago in terms of the teams' collective understanding of the basis from which we go racing."

A sour new controversy over the legality of a car is brewing at the start of the 2010 season - but only, it has to be suspected, because McLaren have trumped their rivals with an idea bordering on genius in its simplicity. And, in time-honoured fashion, everyone else is wondering why they didn't think of it themselves.

The controversy is focused on a small flap that the two McLarens have in their rear wing. The device - and car - was given the FIA's seal of approval on the eve of the season-opening race in Bahrain but further protests are thought to be likely following the race.

But on what grounds? Whilst the exact workings of the 'flap' are shrouded in mystery, it is thought that McLaren are cunningly circumventing the rules outlawing moveable aerodynamic devices because it is the drivers themselves - who are not classified as an aerodynamic device, moveable or otherwise - who operate the flap by using their right knee to cover the flow of air into the cockpit tunnel. This in turn effects the flow of air to the rear of the car and 'stalls' the rear wing.

It's believed that the advantage accrued from the device amounts to approximately an extra 6mph on the straights when the cars are running at top speed.

McLaren, somewhat unsurprisingly, are refusing to name the individual in their company who first thought up the concept, but are confident that their device is not only legal but will flattered by imitation in the weeks to come.

"People will look at what we have got on our car and I would imagine that most teams are now looking for how they would implement such a system," Martin Whitmarsh told Autosport. "I think there was a "what is it?" question initially, then there was "it can't be legal" and now people are starting to understand it there is "how quickly can we implement it?"

"Most people are saying that it was something quite ingenious. This was a very creative and ingenious individual in our company who came up with the idea and we've developed it."

Asked if he would like to identify the individual concerned, Whitmarsh replied: "Maybe in time. Secrets in F1 have a remarkably short shelf life and we will make sure that, in due course, the individual gets quite a lot of credit."

The snorkel on the top of the chassis feeds a duct passing down inside the footwell, its position is some where around the pedals, most probably it runs down alongside the brake pedal\footrest so as to avoid the mandatory padding inside the cockpit. This duct has a ‘hole’ in it to ‘cool’ the driver inside the cockpit. However the duct continues inside the chassis, past the fuel tank and up and over the airbox (probably passing by the hatch fitted high up on the engine cover), then through the shark fin and into the rear wing flap.

When the driver places his foot\leg over the ‘hole’ the flow is diverted into the rest of the duct and this feeds the slot on the rear wing flap. There is enough airflow through the convoluted duct to disrupt the airflow under the rear of the wing, effectively breaking up the flow around the wing. This is what F1 aerodynamicists term a ’stalled’ condition, although this is different to the term ’stall’ used in aeronautical aerodynamics. In this ’stalled’ state, the strong spiralling flows coming off the wing, that lead to the huge drag penalty a highly loaded F1 wing incurs, break up. With out these flows and their resulting drag penalty, the car is able to get to a higher top speed, by around 3-4kph.

The driver isn't a device nor is he part of the car.

The driver adjusts the front wheels and they probably have the biggest aero effect on the car. Perhaps we should ban steerable wheels.