# 6-speed manual on 325i?



## bmw325 (Dec 19, 2001)

gojira-san said:


> I look at the 6-sp as less of a top-end device versus a fuel-economy device. If I remember correctly, the 330 6-sp has better fuel economy than the 325 5-sp. I've been getting 30mpg on longish highway trips, which I am very happy with.


The 5 speed 330 also got better mileage than the 5 speed 325-- i'm not sure if the 6 speed made a difference. the 5 speed 330 was EPA rated at 21/30-- I think the 6 speeds are rated the same...


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## 325SMG (Jan 11, 2004)

robg said:


> The 5 speed 330 also got better mileage than the 5 speed 325-- i'm not sure if the 6 speed made a difference. the 5 speed 330 was EPA rated at 21/30-- I think the 6 speeds are rated the same...


 The 325 and 330 get similar mileage. 330 doesn't have better gas mileage than 325 with the same transmission. The 330 with the 6-speed gets slightly better highway MPG than the 325 with the 5-speed, because of the final gear. But when both are mated with the SMG for example, the 325 gets slightly better gas mileage. I think they get the same mileage with the step.

Refer to this link:
http://www.fueleconomy.gov/feg/FEG2004_GasolineVehicles.pdf


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## andy_thomas (Oct 7, 2002)

SdotR said:


> Sweet! Thanks, that's exactly what I was looking for.
> 
> So that means that the 325 cruises at 80mph at ~3389rpm, and the 330 cruises at 80mph at ~2623 rpm. Does this seem right to everyone? I ask only because calculations are sometimes too "perfect".


Well those figures aren't that accurate - I used figures to two decimal places for the final drive ratios, where you should really use 45/13 for the 325i (=3.461538 etc.) and 41/14 for the 330i. (43/14 for the 330i PP.) Call it 3,400 rpm and 2,600 rpm respectively.


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## SdotR (Apr 12, 2004)

andy_thomas said:


> Well those figures aren't that accurate - I used figures to two decimal places for the final drive ratios, where you should really use 45/13 for the 325i (=3.461538 etc.) and 41/14 for the 330i. (43/14 for the 330i PP.) Call it 3,400 rpm and 2,600 rpm respectively.


Where do you get those fractions from?

Something's strange here. When I run these numbers, I get ~3733 (325) and ~3157(330), for engine rpms at 80mph.

Maybe I'm beating this to death, but chalk it up to the engineer in me.


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## andy_thomas (Oct 7, 2002)

SdotR said:


> Where do you get those fractions from?
> 
> Something's strange here. When I run these numbers, I get ~3733 (325) and ~3157(330), for engine rpms at 80mph.
> 
> Maybe I'm beating this to death, but chalk it up to the engineer in me.


Fractions are from the ETK. A 3.45 rear end is 38:11; a 3.46, 45:13. (AIUI more teeth on the pinion means higher torque use - which is why there are two diffs in BMW's range with ratios only 0.3% apart.)

A 3.73 is 41:11; 3.91, 43:11. 3.15 is 41:13, and the comedy moonshot 2.28:1 from the 330d is 41:18.


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## jm8571 (Mar 3, 2002)

*He who makes the gold...*



robg said:


> I wonder why they bother having different transmissions for the regular manual vs 6 speed. I would think it would be easier/cheaper to just offer the 6 speed across the board.


PROFIT...SMG option has a higher profit margin than a 6-speed manual. By having the only 6s option be SMG, BMW can increase overall profit on the lower-margin 325.


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