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04092008, 04:12 AM  #1 
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Weight difference with different options?
I ve been wondering how much weight do the most popular options add:
 MDCT  Navi (Idrive stuuf)  Premium audio, parktronics, etc. What the power to weight ratio will be with the equiped car then? Thanks. 
04092008, 05:31 AM  #2 
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MDCT adds about 45kg.
Nav (purely a guess!) could be 5kg??? Audio maybe another 5kg???? Difference in power to weight 250bhp/ton for a base Coupe Vs 242bhp/ton for a car with the MDCT etc...... however the MDCT car will still be quicker due to its better gearing and super quick shifts. 
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04092008, 09:23 AM  #5 
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04092008, 10:39 AM  #6 
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Wow, that is nothing!! And NAV would have te be less than 5 kg as well IMO.
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04092008, 12:52 PM  #7 
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Honestly the only real option that will add any perceptible difference in weight are the 18's vs 19's. The 18's save about 46lbs per corner in unsprung weight. That is getting close to 100lbs. If you think about it thats like riding with a trim/short girl in the passenger seat.
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04092008, 01:23 PM  #8 
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the sunroof does add some weight. I dislike sunroofs not just for the weight but the CF < steel < sunroof and the weight is at the top of the car which is almost the worst place to have it.
I think the steel roof is about 10 lbs more than the CF roof and the sunroof adds another 10 lbs. So in other words a sunroof on a coupe is probably 20 lbs more than the CF standard roof. I forget the exact weight but I think it's like 20 lbs. Likely the premium stereo weighs a fair amount with speakers and extra amps those things are not nothing. Last edited by rai; 04092008 at 01:39 PM. 
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04092008, 01:28 PM  #9 
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Unless you are going to be doing extensive timed runs on a track, you won't notice a difference in real life.
As far as being faster than a heavier M3 not only depends on the weight of the car, but the amount of fuel, driver skills etc. In my opinion, you should get the option you want unless you are going to build a track car and plan on gutting it out. 
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04092008, 02:39 PM  #10  
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Except the Vert option which is 400 lbs (I think) I have not driven but likely that's very heavy feeling compared to the least M3. 

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04092008, 02:51 PM  #11  
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04092008, 09:47 PM  #12 
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Actually, GregW weighed the stock 19s with tires and is estimating 23 lbs front and 26.5 lbs rear (give or take a pound after subtracting tire weight). We won't know for sure until someone weighs the stock 18s, but the 19s may actually be the stock lightweight option for this car.

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04092008, 10:32 PM  #13  
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04092008, 10:45 PM  #14  
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04092008, 11:27 PM  #15 
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Thanks. According to the weights listed on The Tire Rack, the 19" rears are 12 lbs lighter than the 18" and the fronts are 01 lb lighter than the 18s. They have several listed of each size so I'm not sure which weight to use, thus the range. I bet the combined tire/wheel weight between the 18s and 19s will be nearly negligible.

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04102008, 02:18 AM  #16  
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this is unfounded. the 19's wiegh less than we thought thanks to greg for wieghing them. moonroof 56# DCT 45 # other misc. options 5# total 106 #. Last edited by sayemthree; 04112008 at 03:25 AM. 

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04112008, 12:33 AM  #17 
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I read that the Steel roof weighs 12 lbs more than the CF roof, and getting the sunroof in the Coupe rather than CF adds 42 lbs. So in other words, getting the sunroof in the sedan should add about 30 lbs over just a plain steel roof.
To me this is real weight that is in the wrong location. Then factor in $1050 savings and I will be leaving the sunroof out.
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04112008, 04:02 AM  #19 
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just weighting the tires on a scale will not give you the true answer.
Moment of inertia needs to be calculated for the wheel + tire. When accelerating the available torque at the wheels will be fighting a greater resistance to angular rotation acceleration if the moment of inertia is higher and that will result in less traction on the road for acceleration. The moment of inertia is proportional to the distance of the mass to the centre of rotation squared. So 18 to 19 inch can still make a 11% increase even if the tires weight the same. 
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04112008, 07:07 AM  #20 
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That is correct and I touched on it in my post. I still bet it is going to be close between the two stock sizes because the 19" tires look to be a pound or two lighter than the 18s. Maybe that will help offset some of what the rim difference is because the tires are even further from the center.

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