# Final drive ratio for 3-series and gas mileage



## rumratt (Feb 22, 2003)

I'm trying to find the final drive ratio for 325 i/xi/iT/xiT with manual transmission. bmwusa.com's new format lists multiple drive ratio's for each car, but doesn't say when they apply (see below). 

Is the following correct for manual transmission?

325i: 3.15 (EPA: 20/29)
325xi: 3.23 (EPA: 19/27)
325iT: 3.46 (EPA: 20/29)
325xit: 3.46 (EPA: 19/26)

Interestingly, the gas mileage of the 325i and 325iT are identical.  xi hurts mileage for both, but more for the wagon. Odd.

Also, does anyone know the approximate engine RPMs when cruising at 70mph with the 3.46? 4000 maybe? I know the engines are perfectly happy (and quiet) at 4K so if the gas mileage is the same, I guess it's not a big deal.



from bmwusa.com for 325i said:


> Transmission
> Automatic gear ratios 1) 3.67/2.00/1.41 I/II/III
> Automatic gear ratios 1) 1.00/0.74/4.10 IV/V/R
> Final drive ratio 3.46 :1
> ...


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## Kaz (Dec 21, 2001)

I think it's [email protected] 250rpm for every 5mph in 5th. I think the 3.46 MT setup is the only one where the speedo 'chases' the tach. I think a 6th that will get RPMs @70 down to say 2800 would help fuel economy in freeway driving.

Frankly, I don't know how those EPA numbers were achieved. Even a constant 60MPH on perfectly level ground won't get me 29MPG. Maybe they used 60psi electric car tires or something.


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## rumratt (Feb 22, 2003)

Thanks Kaz. If it's really 3500 at 70 that's not too bad. If you're going over 80 and it gets above 4K that might start to get annoying.

Isn't it ironic that my 330 has a 6th gear that I never use, while those with the 3.46 are driving around near 4000 RPM.  

Maybe if I end up with a 325iT I'll do a DIY tranny swap. :eeps:


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## Nick325xiT 5spd (Dec 24, 2001)

It's 3.23 for manual xiTs, unless BMW's changed something.


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## Nick325xiT 5spd (Dec 24, 2001)

And Kaz, I get an average of 28MPG on long distance highway drives averaging around 80MPH.


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## rumratt (Feb 22, 2003)

Nick325xiT 5spd said:


> And Kaz, I get an average of 28MPG on long distance highway drives averaging around 80MPH.


Can that possibly be right? 3.46 for iT and 3.23 for xiT?


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## Nick325xiT 5spd (Dec 24, 2001)

rumatt said:


> Can that possibly be right? 3.46 for iT and 3.23 for xiT?


 3.23 jibes with my calculations based on RPM and speed.


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## rumratt (Feb 22, 2003)

Nick325xiT 5spd said:


> 3.23 jibes with my calculations based on RPM and speed.


Nick, this BMW brochure for '03 models confirms what you said www.bmwpro.com/03-3-touring.pdf . The iT has a 3.46 with manual transmission, and the xiT has a 3.23

Am I the only one that finds this odd, that they gave a lower final drive ratio to the xiT, which is even heavier than the iT. Maybe they needed it to keep the fuel efficiency from being a disaster in the xiT? Even with the lower rear ratio, the xiT is rated at 4mpg worse for highway EPA. Ouch.


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## Nick325xiT 5spd (Dec 24, 2001)

Yeah, well, *I* would prefer the 3.46.

And I wouldn't complain about a 3.63.


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## bmw325 (Dec 19, 2001)

rumatt said:


> Thanks Kaz. If it's really 3500 at 70 that's not too bad. If you're going over 80 and it gets above 4K that might start to get annoying.
> 
> Isn't it ironic that my 330 has a 6th gear that I never use, while those with the 3.46 are driving around near 4000 RPM.
> 
> Maybe if I end up with a 325iT I'll do a DIY tranny swap. :eeps:


It is very ridiculous. ITs the smaller engined cars that could really use the 6 speed-- but for marketing reasons, BMW only offers it on 3.0 cars to add to the "performance" image.


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