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Discussion Starter #1
Any idea whether it will get the carbon fibre treatment like the M3? I would have thought it will need all the weight saving it can get.
 

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Doubt it very much. A CF roof has only been offered on coupe's so far. The E90 M3 did not have one.
 

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Discussion Starter #3
Doubt it very much. A CF roof has only been offered on coupe's so far. The E90 M3 did not have one.
That's an interesting point. Is there an engineering/logistical reason why the M3 coupe had a CF roof and the saloon didn't?

The new M5 will have to handle better than the outgoing M5, it will have to beat it around certain benchmark circuits (as well as beating the competition ie Audi RS, MB AMG). Given the normal F10 has gained weight, how will it do this unless it sheds some of this weight via CF parts? The only other solution is trick suspension and lots of power, but others have tried this and failed. The only exception being the GTR.
 

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The weight-saving of a CF roof is negligible, though it reduces it at the second-best place: the top (the best place is unsprung weight). A CF roof also precludes the normal sunroof.

Given that the M5 is a large/heavy sedan, I certainly don't expect the use of expensive and feature-limiting CF to achieve almost nothing.
 

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The CF roof on the E63 M6 shaved 10 lbs off the roof (and yes, that's the best place to have a savings).

Remember that the M3 coupe (E92) has a CF roof but the M3 sedan (E90) does not as it typicaly comes with sunroof (in the U.S. at least). BMW has found that 4 door sedan owners expect a sunroof which is already a weight and center of gravity hit, so CF is sort of meaningless on a sunroof car (except for coolness factor of course).

Having said that, the new F12 6 series cars (640 & 650) are reported to come with a plastic composite roof (but not CF) and I expect the F12 M6 to have a CF roof again. F14 Gran Coupe M6 (if they build it) may or may not depending on if a sunroof is available on the M6 variant.

So, back to the F10 M5...

If they do offer a CF roof, expect it to not have sunroof and to not sell that well compared to a steel roof/sunroof equipped M5. Just my guesses...
 

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Discussion Starter #6 (Edited)
Thanks, the sunroof thing did not occur to me.

On the other point I wasn't trying to say that a CF roof would save loads of weight but saw it as a commitment to TRY and save weight, with perhaps CF or lightweight materials used elsewhere.

So how will the M5 save weight or counter that weight for handling purposes? Or will it end up like an Audi RS6 ie a 2 tonne behemoth that can't disguise its weight in the corners?
 

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Doubt it very much. A CF roof has only been offered on coupe's so far. The E90 M3 did not have one.
But also keep in mind the M3 has variants, I am wondering if because the M5 may ONLY be a sedan (touring maybe, but wouldnt get CF) that BMW may find a way to add a CF roof.

They own that CF production company, I may not expect a CF roof but there should be some CF structural bits to the car
 
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