Originally Posted by Uli_HH
And if you think about the carbonparts of the F80, you shouldn´t think at carbonroofs like the old M3 or the new M6 ... I guess little or nothing of this parts would be visible because they consist of parts such as shaft drive / transmission tunnel, lock-makers, engine and luggage compartment rear wall, crash boxes and wheel mounts and axle stools. All parts that must be structurally strong and solid and so are relatively heavy in steel.
If you now imagine that this parts are produced of very light and relatively favorable industry-carbon composite (two layers of carbon with a layer of cardboard / paper in between) , you can easily imagine the weight savings in these dimensions.
The produced in relatively small quantities F80M3/F82M4 will be the first application of this design before getting it in the next 7-way into the AG mass production.
So ~3.200lbs seems not impossible!
I'd bet against 3200 lb, again strongly bet against it.
Cheap core materials like cardboard can provide stiffness improvements in large sheet like structures but would not be used for more complex mechanical/structural type shapes. Due to language difficulties (wheel mounts, axle stools ?) I am not positive, but many of the items you list do not seem like good candidates for replacement by CF, certainly not a CF/cardboard sandwich.
We keep hearing about the capabilities BMW gained when they purchased a large stake in SGL Group. However, they are touting much of the CF production from their new Moses Lake, WA facility to be slated for the i3 and i8 vehicles. They are also claiming that their new industrial (as opposed to aero******* grade CF will be about 50% the cost of traditional aerospace CF, thus about $10/lb, still over 10 times
more expensive than steel.
For the sake of argument if they want to save 300 lb with CF that will take about 100 lbs of CF replacing 400 lb steel (super coarse "back of the envelope" estimate here). That will then cost just in materials at least $1000, not to mention higher tooling (fixed) and much higher labor costs (variable). I'd estimate the total cost (not price, cost) to save 300lb at about $1200. That must be increased further by their desired profit margin. It may not sound like a lot in a $60k car, but you would be amazed at what large automotive OEMs will do to save a few pennies on simple things like fasteners. $1200 is a HUGE expense.
Again there will be innovation, there will be weight savings, there will be increased use of composites, CF and lightweight metals. The car most likely will weigh less than the outgoing model. However, 3200 lb is just not going to happen.