well, still keeping the v10 in there... or have that v8 still produce that 500 hp and how much ever torque... just take out the luxuries like the ac and stuff...
im not sure how much all the electronics would weight, but i think 600 pounds seems like a good estimate... so .6 to put it in the lower 4's??? i guess its not all that worth it... unless my estimate on the weight is severely off... it could be..
Your calculations aren't too accurate. The role weight plays in performance is a bit more complicated than just thinking that weight always equals a deterioration in performance. Yes, a lightened car with the same engine as before should perform better overall, but there are certain aspects that will yield different results.
While I don't know how much extra weight all of the amenities in such a BMW actually equates to, it *may* have a different effect on the actual launch from a standstill, as weight (especially its distribution) can sometimes aid traction, which is why featherweight cars like the Lotus Elise have relatively tiny and torqueless 1.8-liter engines but can still run low-13s in the quarter-mile, despite only having 190 hp and 133 lb.-ft, though it's really all that's necessary. Hypothetically speaking, imagine that you drop a 4.6-liter V-8 from the current Ford Mustang GT, so in the same car you've got an extra 110 hp and 187 lb.-ft. It might sound fun, but in a car that light, there won't be too much weight resting on the tires, and that much torque over such a broad rpm range will have you hardly moving at all while peeling out from a standstill until you almost completely back off of the throttle and let the tires catch. (Doing the same in a lightweight AWD car will have different results, as traction won't be an issue.) But once you're moving (and we're talking about the M6 again now), the lower weight will now be a lot more noticeable once you start moving, especially in a longer run like a quarter-mile. Check this article out for further proof:
http://crazyjim.ramelot.com/14seconds.htm
What they did here was take a relatively unmodified (at least from a performance aspect) Nissan Sentra and strip it down until it eventually was a full two seconds quicker through the quarter-mile (though it's an understatement saying "strip it down," as you'll see when you check the article). Notice that throughout the incremental decreasing of the car's weight (an overall difference of almost 1100 pounds), a lot of stuff changes drastically... the quarter-mile time (2.0 seconds faster), the quarter-mile trap speed (9.2 mph faster) and 0-60 mph acceleration time (2.8 seconds faster). But the 0-60 foot time fluctuates very little (up and down, rather than always down like the other improvements) throughout the increments compared to the other performance measurements at each weight stripping. Only toward the end does the 0-60 ft. time drop nearly as drastically (as a 0.3 second difference in 0-60 ft. time is a pretty big deal in itself). Like I said before, while the car has the benefit of having less mass to accelerate from a standstill, the weight on the driving wheels changes, thus altering its ability to grip for a better launch throughout the experiment.
I don't really know where I was going with this, as I have typed up a bunch of shit, but I suppose what I was saying was that it would be hard to estimate what impact certain weight saving methods would have with reasonable accuracy considering the various factors involving physics. The general rule of thumb I was speaking about earlier (the 100 pounds = 0.1 seconds thing) obviously isn't always accurate, as seen in the link I provided, plus a unit like 100 pounds is obviously a bigger deal to a car that weighs 2762 pounds than it is to a car that weights 3762 pounds.
My head hurts.
