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      07-18-2013, 02:33 PM   #92
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Drives: 2015 M3 6MT
Join Date: May 2013
Location: Seattle

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Originally Posted by swamp2 View Post
The rear seats are indeed about 45 lb. As some useful reference material here is a great thread on how much it costs with aftermarket parts to save a given amount of weight in the E92 M3 (link).

So yes, indeed one has about 170 lb (again based on link above) to work with for seating weight in the E92 M3. That also assumes the 435i seats haven't already undergone some lightening work which surely they have. You can reduce the weight on many fronts, leather, foam, electronics and most importantly the motors and steel frame parts. There is very little steel in the rear seats and no motors. Thus the vast majority of the savings will come only from the front seats. The challenges are that M3 owners expect a daily driver. You can't put non power seats in, some may call that sad, but it is the reality. You also can't make really firm minimal padding seats. BMW also won't sacrifice on safety. Thus if a seat airbag got nixed it would probably migrate to a door. Last but not least carbon fiber is extremely expensive. So thus again, 50 lbs is roughly 50% of the front seats and that is extremely aggressive and doubtful.

Look again at the link above using BMWs own seats already available:
  • BMW performance bucket seats with side airbag: 55.7 lbs
  • Weight savings 14 lb (both front seats)
  • Cost $5000 (back in 2008 from Turner Motorsports)

IT COSTS A LOT OF MONEY TO SAVE WEIGHT! Sure that is not BMWs cost but fancy light seats with safety are darn expensive and not consistent with BMWs agressive cost savings programs.

Anyway back to the M4. A modest perhaps 30 pound savings is certainly possible. However, BMW may provide and optional seat, likely IMHO, such seats could be more extreme in design, not have motors and save way more than 30 pounds. But again they will be expensive and optional.

I'm not being a pessimist here, just an informed realist.
But you are being pessimistic. According to this link more could be saved but BMW choose to make the CRT's comfortable with ample padding. This link also touches on the potential link between the CRT and the F80:

Furthermore shows the 3 liter TT N54 at ~$11k and the S65 at ~$23k. The S65 is standard in the most basic M3. There should be room to spend significant $$$ on lightweight materials within reasonable end cost. The i3 and i8 also brought potential to share in R&D and production materials for CF parts plus added volume advantages. This could make earlier cost prohibiting constructions within reach for the M3's price point.

Time to be positive and look at possibilities and not be so negative with potentially old limitations. They kept the M5 pretty much the same weight as the 550i without the CRT treatment. Now if they do the same with the M3 vs the 335i and then add the CRT treatment and lighter wheels they are in striking distance of 3300 lbs without doing anything they haven't already done. Then add a few innovations and what do you know? Maybe it's not such a stretch after all.

Last edited by solstice; 07-18-2013 at 02:39 PM..