Formula 1 bosses are split on the timing and implementation of rules intended to make cars more exciting.
All are in favour of a plan to make cars look more dramatic but there is disagreement on whether changes should be made for 2016 or 2017.
Red Bull team boss Christian Horner wants change quickly, while Mercedes believe more time should be taken to ensure the right decision is made.
There is also no agreement on how to achieve the goal of 1,000bhp engines.
The complexities of the chassis arguments are being played out at a meeting of technical chiefs on Friday, the remit of which is to draft a set of rules for 2016 that can be agreed by the next step in the rule-making process, the F1 Commission, on 17 February.
The main points of agreement are:
- Wider cars, reintroducing the maximum width of 2000mm last used in 1997 instead of the current 1800mm, and a lower rear wing.
- Wider rear tyres
- To increase the power of engines to 1000bhp from the current 850bhp or so
The main disagreements are over:
- The timing of the change - whether major changes should be made for 2016 or delayed until 2017
- The need for research to ensure it is the right approach
Who wants what, when and why?
Red Bull are pushing for modifications to the cars and tyres in 2016. Some believe this is because they think it will help them reduce the significant advantage Mercedes have held since the introduction of the new engines last year.
A change for 2016, sources say, was agreed by a majority vote at the last meeting of the F1 strategy group of leading teams, F1 boss Bernie Ecclestone and governing body the FIA.
But Mercedes are pushing against this, believing F1 should conduct research with fans and audiences to see whether this is what they want.
The desire for change is being driven by declining television audiences in some key markets - although numbers have gone up in some countries such as the UK and USA.
Mercedes have also been arguing in meetings of F1's rule-making strategy group that to introduce new rules too early would have a detrimental effect on the 2015 season. They say the short timetable would lead teams to stop developing their cars for this season to concentrate on the new designs for 2016.
The same would apply if the change was made for 2017, but the longer timescale would mean the change was easier to manage.
Ferrari occupy a kind of middle ground.
They have an overall desire to reduce costs and improve the show. They accept that major changes to the cars would have to wait until 2017 but believe smaller modifications could be made for 2016.
In addition, a formal tender process will be conducted to choose a new tyre supplier after the end of Pirelli's contract in 2016. Tyres will be of lower profile, with 18-inch or even 20-inch wheels being discussed to replace the current 13-inch designs.
Is it the right approach?
The agreement to introduce wider cars, tyres and more powerful engines was described by one team boss as "the lowest common denominator" - the only thing all could agree on.
But it is based on an idea that returning the look of the cars to those of 1992-93 or similar would increase the audience.
However, some argue that could be because it was an era many of them find evocative as it was when they were growing up and first became fans of F1.
So Mercedes team boss Toto Wolff has proposed that F1 conducts research to see whether this is indeed what the younger fans of today want.
Return to old engines rejected
Ecclestone, F1's commercial chief, has been a staunch opponent of the new fuel-efficient engines since their adoption was agreed six years ago and has tried several times to get them dropped.
He believes they are too expensive and too quiet.
But all four car manufacturers involved in F1 insist on keeping the current engine format, with systems that recover energy from both the rear axle and turbocharger retained because of its relevance to road car technology.
Ferrari president Sergio Marchionne had proposed a new hybrid format, based on a 1.9-litre V8 turbo engine, claiming it would be cheaper.
But he backed down on this when it was pointed out to him that changing the engine architecture could well mean Mercedes ended up further ahead, because their engine department is regarded as the best in F1.
Mercedes have proposed removing the fuel-flow limit on the current engines as a way of increasing power, which is currently in the region of 850-900bhp.
But Red Bull believe this would force a major redesign that would be too expensive for the other manufacturers, especially their supplier Renault.
Red Bull have proposed a freeze on the hybrid aspects of the engines with development limited only to the top half of the engine - cylinder head, valves and so on.