This is really a stupid post as I already know the answer. I've read through most of the "auto vs. manual" stuff but for me (FOR ME) I made a mistake getting the stick. At 60mph the RPM's are simply too high and I keep getting the sense I'd like a seventh. Given the gearing differences I would love to hear exactly what RPM the Sport auto runs at 60MPH. I'll drive mine today and try and remember what it shows me, but I believe it's near or at 3k. Consumer Reports preview of the standard auto and manual Sport notes about a 750RPM difference. Why couldn't I get the standard model w/cruise control? Forgive me, I digress.

This makes for an engine hum that's excessive, again, for me personally. More importantly (for me, and probably not you) is the loss of fuel efficiency. I fully realize I would be considered a bit of a compulsive about it, but I did come from an '07 Prius. On the up side, the M5 shifts so nicely that's it's nearly transparent. At least in comparison to the '08 Tacoma M5 I have. For those who relish driving a stick I'm spouting blasphemy but I'd just like a gearing change, not

I also drive a Suzuki 650 V-Strom bike and added a tooth to the front sprocket (easy, cheap) which lowered RPM's ~8-10%. This was a good upgrade, again, for me. Acceleration losses are not an issue as you simply select a lower gear for any given speed/desired acceleration yet add efficiency on top. Ok, first gear is higher and not something that's operator adjustable.

So, here comes the stupid question. Is there any way to increase the final gearing that doesn't involve a bazillion dollars? I don't know if taller wheels fit the Fit and I don't want to buy all new tires/wheels anyway.

gary

 

you are correct about rpms at 60mph, it is dead on 3k RPM

BUt to me the fun factor of the manual well outweighs the 5th gear rpms. Plus if it wasn't this high the car would probably not have enough power to climb tall hills, which would require a lot of unecessary shifting.

 

Yup, I just checked. I'm around 2.9k RPM's at an indicated 60mph. On the up side the speedo is proving to be remarkably accurate based on gps readings. Most other car speedos are 2-7mph fast at 60. My Tacoma, Yaris and previous cars were all that way. The Prius was just 1 mph off. I'll need to check further, but it looks as if the Fit is at least as accurate as the Prius was. My UJM's have all been at or near the 8-10% inaccuracy. gary

 

You'll need a new gearbox not just a sprocket.

 

This is why I went with an auto....quieter on the highway, better fuel economy....easier for the wife to drive as well.

 

Funny thing is, though I have the manual, I've driven the automatic a few times, recently on the highway and I didn't at all notice a difference in noise due to the difference in revs. I wasn't looking for it, but at the same time I didn't notice it. At 60 mph, I don't hear much of the engine with my manual.

Have you driven the auto on the highway?

 

my other cars are 6MT, so i keep thinking i have 6th but then i
have to remind myself that i dont.

my car is driven 99% surface roads under 55mph so 5MT is
perfect for me.

 

I was able to calculate from gear ratios and tire sizes that the automatic runs at about 2100 rpm at 60 mph in top gear, and the manual about 2800 rpm - numbers rounded off. That enables the automatic to be quieter at highway speeds, and competitive in fuel mileage. It also assures that the automatic will have worse acceleration in terms of 0 - 60 times.

We have ordered an automatic on account of my wife's inability to drive stick. However, if I were ordering only for myself, I probably would take the automatic for the more relaxed top gear ratio. In my 'other' life, I have an aging Garage Queen Honda S2000, which has a six speed manual transmission. This is a car with a 9000 rpm redline, and it runs about 3300 rpm at 60 mph with this close ratio 6 speed. A higher top gear would not work well on the S2000 on account of the engine's ultra high revving design.

 

Keep in mind that just because the engine is spinning faster, it doesn't necessarily mean more noise. Example, my Integra's engine could be heard at 60-65 mph, but silent at 75.

 

cause you shut off the engine at 75mph and coasting?

 

Now I'm actually curious if the manual is any noisier than the taller-geared auto at highway speeds. I can say at up to 75 mph on my MT, there's a distant hum, not even noticeable. By 80 mph, it's a much more noticeable hum.

Again, driving my parents' new 09 AT on the highway, I didn't notice any noise difference, but at the same time I wasn't looking for it.

Anyone out there with access to both MT and AT 09 Sports, we need your help.

 

i have noticed this, but its not something that i mind that much.

i have a 09 5speed

 

Differing rpms for sure have a different pitch . . . but as for actual volume, the difference is negligible.

Throttle position is a much large variable in volume than rpms. So depending on the engine, keeping it in 5th gear at 70mph could be a lot quieter @ 3k rpms than it would be at 2k . . . The engine is more efficient & can produce more power at the higher rpm, so less throttle is required. And even though a higher rpm means more injector pulses & fuel required, in many cases there is no detriment to fuel efficiency - the engine can do the work it's required to without excessive throttle, and stay off the high load fuel-rich maps in the computer.

What's better - accelerating for 45 seconds @ 85% volumetric efficiency, or accelerating for 10 seconds @ 40%? Depends on the situation . . . but the point is, high(er) rpms are not necessarily the mpg killer people think they are.

 

Actually, and subject to further review, it's my understanding that a particular engine's peak efficiency is the RPM that at which peak torque is generated. That's only one of a bazillion variables in fuel economy, but it is one. Obviously weight, rolling and wind resistance, etc all play their parts in varying degrees. Since I'm not smart enough to calculate even a few of these combined, I'm just going to assume that my Fit would be more efficient at a lower RPM. I've not seen a torque/HP comparison chart for the Fit, and can't remember the one I looked at on my bike. But I do know that the taller front sprocket improved fuel economy, decreased noise at highway speeds, and decreased available power at identical gear position and speeds (easily overcome in all but first gear). I tour rural central northern Canada a lot so the increased range was a big factor in my decision. The decrease in engine noise was inconsequential as wind trumps engine noise. For me it was worthwhile farkle, for most probably not.

Given the inherent inefficiencies of the automatic, I realize now that it's still more fuel miserly at highway speeds compared to my M5. But, that's the way it is. I researched here a fair amount before buying but missed that point, my fault.

As far as economics go, I did calculate costs of fuel when I bought the Prius in '06. It turns out that going from 14 to 16MPG on a pickup is far more significant than going from 30-35MPG's. So, I also realize that my musings about the Fit are in reality pretty much a moot point. Doesn't mean I can't ponder it though. Having said that, I can see biting on a 2011 Prius of Insight as I don't like buying first year design/redesigns, even from Toyota or Honda. This coming from someone who just bought a redesigned '09 Fit?

So, a little more research would have been in order but now it's done. And overall, while not as nice as the Prius, the car was $8k cheaper and does have several features that I like better. gt

 

According to dyno graphs I've seen, the L15's torque peaks at ~3,500 rpms. Although "peak" isn't a great descriptor, it more accurately plateaus . . . But that's why the car is geared the way it is - maintaining highway speeds in a car that's relatively underpowered requires it to be operating near it's peak torque rating. Any rpm less efficient (torque-wise), and you're looking at excessive throttle usage, and the need to downshift a lot more. The automatic's are able to be geared longer because they can downshift under cruise control to make it up a grade.

And yeah, although peak torque is peak efficiency - it doesn't equate to peak fuel efficiency. Like you say, there are at least a dozen other variables to consider.

In my experience driving Honda's, their generally higher cruising rpms are not a negative factor in fuel efficiency. For example, my Prelude maintains peak fuel efficiency cruising up to 4000 rpms.

Actually - 30->35 is a more significant improvement than 14->16 (although only just) It's a 16.6% improvement vs. 14.3% . . . But I know exactly what you're saying - the gallons-per-mile calculation that people should look at. Although I think it's easier to wrap ones head around it viewed as a percentage of improvement.

 

You can take your car to good audio shop and have sound deadening mat applied to the firewall on both sides, maybe on the hood - they will know what to do. It might cost a couple of hundred bucks but I think you will be pleased. Or, do as I do, keep the audio above 100 db!

 

Folks, not only are the EPA figs for both AT and MT equivalent, but our own reportings of our mileage here suggest that they're essentially the same. So going back to the OP's real topic, it was a question of noise at the same speed, not FE.

 

:shrug:
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