I could be wrong though !!
Indeed you could.
I guess there is a chance that the basic tub still has some DNA back to the Honda or Brawn era, but that means bugger all really, everything that really matters would have changed since then.
Brawn said the BGP001 had compromises, the biggest was that it was designed around the Honda engine, when Honda pulled out and they got hold of the Merc engine it had to be mounted higher (raising the centre of gravity), not ideal.
No chance they would have left that compromise in for 3 years.
Also, amongst other things the regs this year required front suspension mounting points to be a certain height from the floor, thus creating the stepped noses we've seen this year, so that'd be another change.
If there is anything left of a Honda/Brawn tub its probably the small section where the driver parks his butt - engine mounts, front suspension points, sidepods will have all changed.
Apart from some KERS reliability issues I think the main problem with the Merc has been that they haven't got on top of the aero.
Last year they were quick in a straight line, often topping the speed trap figures. Problem was, it sucked in corners, the car would slide, prematurely wearing the tyres.
This year its been better (but far from good) but they have lost their way developing features that haven't worked that well (DDRS & coanda exhaust).
They need better basic aero and need to work out how other teams are making the flexi wings work so well and stay within the regs. They also need some good data techs to understand the data to help them read the tyres.
Daimler have bought out Aabar's share in the team and I hear that there is significant investment in R&D for next year's car, which they have apparently been developing for a while. Lets see what they can do.
Many people think the big changes will come in 2014 with the new engines, it'll be interesting but I still think the dominant factor is aero.