This is a compilation of what we've found so far, Please add more.
* 'certainly the underfloor was going to produce more downforce, while the nose tip will be lower, something like 17cm off the reference plane…' Scarbs F1 Blog.
* 'Up to 80% of total downforce could be generated by the floor alone' somewhere on F1T, can't remember.
* 'Chassis height limited to 550mm' (2012, possible further reduction, this is at 1000mm in front of cockpit entry template). source : FIA regs
* A far greater proportion of the total downforce of the cars will be created by the underfloor, compared to the wings;
* A major reduction in the amount of total downforce created by the car;
* To achieve this, the underfloor of the cars will be shaped along its length to generate downforce for the first time since the 1982 season - currently cars have bottoms that are flat between the wheels;
* The average proportion of a lap that a driver is able to spend on full throttle to be cut from 70% in 2010 to 50% in 2013;
* Front wings will be raised by 75mm and width reduced by 120mm and all appendages put on the top of the wing be banned, think back to when the current wings were brough out in 2008 post season testing by McLaren and Honda.
* Nosecones must be lowered by 200mm to aid the drivers visibility.
* Rear wings will largely remain the same.
* Diffusers will have a standardized central profile in the middle 250mm
* A Standardized KERS/HERS system will be made available for the first time.
* The goal is to reduce the downforce levels by 60% on current levels, but in reality this will be to 40% of present by the time the 2013 cars roll out.
* Spec fuel tanks will be supplied, and all cars must be full with fuel to within a +/- of 5KG at the start of the race of around 850Kg and be at minimum 700Kg for the end of the race.
* Wheels will be increased to 19" so to make tire technology similar to LMS and road tires.
* Tires are rumored to be 3 spec compounds at each race, with 2 hard, 3 medium and 4 softs per weekend usage, and 4 sets of wet and inters, one set of wets will be in parc ferme for the race from the start of the weekend for each car.
Sources: *
http://www.vivaf1.com/viewtopic.php?t=2370
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http://scarbsf1.wordpress.com/
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http://twitter.com/#!/scarbsf1
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http://argent.fia.com/web/fia-public.ns ... 2-2010.pdf