Formula 1 teams have agreed to abandon plans to make radical changes to cars for the 2013 season.
The teams want to pursue a less radical package of changes that will keep cars similar to current ones but still reduce drag and cut fuel consumption.
The FIA has until the end of June to decide whether to force through its plans against the teams' wishes.
The FIA commissioned respected engineers Patrick Head, director of engineering at Williams, and Rory Byrne, former chief designer of Ferrari, to come up with a new set of car regulations.
The aims were to help reduce fuel consumption by 35% in tandem with a switch from the current 2.4-litre V8s to 1.6-litre turbo engines with 'green' technology and for the cars to be more challenging to drive while being no more than five seconds slower per lap.
The biggest concern [about a 'ground effect' underbody] was that it's a massive amount of investment for the teams; it's quite a big departure
Sam Michael Williams technical directorBut the teams, through their umbrella organisation Fota, felt this would require a lot of work and expense and that the aims of the FIA could be achieved in a way that, as one insider put it, required "less pain".
Instead, a number of detailed aerodynamic restrictions will be introduced to reduce drag, but the current design of the underside of the car, with a stepped but flat floor, would be retained.
These changes, it is felt, will achieve the same targets as those set by the FIA, but the cars will not be as aerodynamically efficient as had initially been hoped.
The so-called Fota rules - which were drafted by Byrne - were
agreed at a meeting at the Turkish Grand Prixand then approved last week by F1's technical working group, which comprises top engineers from the teams and the FIA's race director Charlie Whiting.
The changes agreed will include:
* a front wing of reduced width, down from from 1800mm to 1650mm
* a much shallower rear wing, similar to those used at the high-speed Monza track
* significantly lower noses on the cars to improve safety, although the exact maximum height has still to be determined
* the retention of the moveable rear wing - or drag-reduction system (DRS) - that was introduced this season to make overtaking a little easier
* a restriction on all the extra pieces of bodywork that have sprouted in front of the sidepods of the cars
* a restriction on the design of front-wing endplates, to limit the intricate designs seen today
* a plan to increase wheel diameter from 13 inches to 18 inches has been delayed until at least 2014
We think the DRS has been effective and if we decide not to continue, it's easy to go back on it
Sam Michael Williams technical directorIn theory, the agreement at the sport's Technical Working Group (TWG) means these are the rules that will be adopted after they go through the various stages of F1's regulatory process.
But it remains to be seen whether FIA president Jean Todt will want to accept the Fota rules.
He has been determined to make F1 much more sustainable and efficient with rules changes from 2013.
If the Fota rules are adopted, the cars will be less efficient - with a higher drag - than if F1 plumped for shaped underfloors.
The cars' drag co-efficient will reduce from existing levels of 0.9Cd to about 0.7Cd, while the FIA's initial hope had been to cut it to 0.5Cd.
The teams believe they can still achieve the FIA's objectives at a much lower expense with the revised rules - and the FIA is already introducing a fuel restriction for 2013, so can control consumption that way.
But if Todt wants to make a statement about sustainability, he may feel that he would prefer the teams to be using more efficient cars with less drag.
Todt has generally taken a consensual approach to F1 since becoming FIA president in October 2009.
However, he said at the Turkish GP that he was determined to push through the adoption of the new engines despite growing opposition from the manufacturers, including powerful Ferrari.
The FIA, which can impose rules for 2013 without the teams' agreement if it acts before the end of June, was unavailable for comment.
Todt is expected to have discussions on the subject with key figures at this weekend's Spanish Grand Prix.
Williams technical director Sam Michael said the teams had been reluctant to go down the route of a shaped floor because it involved a lot of work and expense and there were uncertainties over the outcome.
"The only point of contention between Fota and the FIA has been on the tunnelled floor, having a shaped undertray," Michael said.
"Everything else is pretty much the FIA proposal, or pretty close to it with just some tweaks.
"The biggest concern was that it's a massive amount of investment for the teams. It's quite a big departure.
The wide front wings and big rear wings of this year's car will go in 2013"If you were going to go down that route and have a very different set of drag and lift coefficients that you couldn't achieve with the current rules, fine, that's different.
"But the teams saw it as a massive amount of investment and work for something we don't really understand.
"We're not scared of that but if you do spend all that money, why do that and not something you can get to very quickly and cheaply with the current floor. The FIA understood that in the end.
"There's the budget effect of doing the tunnelled floor, a shaped undertray, but there's also the fact that it's unknown.
"So you could predict the downforce you'll get from it, but you could easily achieve double. Whereas if we stay with the current floor, you can be controlled where the downforce and drag are going to be."
The inclusion of the DRS in the 2013 rules reflects a feeling that the device has been successful since its introduction this season.
Michael said: "We think it's been effective. And if we decide not to continue, it's easy to go back on it.
"If all the teams decided later it wasn't useful, we could easily get rid of it. It's not a fundamental design, whereas something like the curved floor is."
