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      07-14-2013, 03:15 PM   #9
swamp2
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Drives: E92 M3
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Quote:
Originally Posted by solstice View Post
IMO you are cutting BMW to much slack on weight if you resign to that 3300 lbs is not doable. A Porsche 991 has all the latest tech and safety equipment and weigh in at just over 3000 lbs. if BMW's main design focus is now weight reduction for the F80 and they have admitted increase of lightweight materials as plastics and CF I don't see why 3300 lbs is a stretch for the admittably bigger car but 3300 lbs is a bigger number than 3000 lbs. Weight increase is not linear to size increase since not all parts grow with the exterior like the engine, tranny, front seats, wheels, and electronics for example.

I have a feeling that the F80 can shave the 200 lbs from the ~ 3500 lbs F30 335i purely by replacing steel with alu in certain weight critical areas even with the added beef to areas as brakes etc. I don't think the F30 is especially big on alu.

I don't care much if the F80 produces 390 or 490 hp but I will be dissapointed if it's 3500 lbs instead of 3300 lbs.
A comparison against a smaller car (Porsche) isn't fair. The Porsche is a bit wider but much shorter than a 3er. Also it's greenhouse is much smaller - the width between driver and passenger, "rear seat" room and overall interior volumes are entirely incomparable. Thus the Porsche isn't lighter because Porsche does a much better job at weight consciousness, it's simply basic math.

Weight increase is probably generally linear with volume (say overall max WxHxL). The best data I could find shows how well weight scales with wheelbase x width. I'm confident you could add height into the comparison and thus compare weight vs. volume and it would be pretty well linear. Yes there is plenty of variation around a perfect line but there is still a linear fit here with good R^2 value (goodness of fit).

The E9X M3 already offered aluminum in place of steel on many large weight components (subframes) as compared to the base model. Without a major migration into the unibody (which isn't going to happen) I'm just not sure how much room is left...

The real question is how well have they done getting composites much less expensive so the bean counters will allow more very light weight carbon fiber and other composites into the car.

Weight will be a big test here for BMW M with this car. We will see if they have the same double speak like they did with the M3.

BMW said "increased use of light weight materials", "light weight design" and "lighter components". What it all ended up meaning was simply less weight increase rather than a lighter vehicle.
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E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK |
| Vorsteiner Ti Exhaust | Matte Black Grilles/Side Gills/Rear Emblem/Mirrors |
| Alekshop Back up Camera | GP Thunders | BMW Aluminum Pedals | Elite Angels |
| XPEL Full Front Wrap | Hardwired V1 | Interior Xenon Light Kit |
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