I own a manual and had it in the shop yesterday for the 10k mile service. I got an auto as a loaner and noticed something about the tach. At 80 mph my manual is at 3400 rpms and the auto was at 2700 rpms.

I know it comes down to gearing and such, but I was always under the impression that a manual transmission give better gas mileage. It obviously isn't due to lower rpms at highway speed. I don't think there's anything wrong, just different.

Any thoughts?

 

The TSX Automatic has better fuel mileage than the 6 speed.

EPA Estimated Fuel Mileage (city/highway)

Manual: 22/29* mpg

Automatic: 23/32* mpg

 

Gear Ratios TSX Automatic TSX Manual

1st 2.652 3.267

2nd 1.517 1.880

3rd 1.082 1.355

4th 0.773 1.028

5th 0.566 0.825

6th NA 0.659

RPM is a function of gearing.
From the above it's easy to tell that 5th gear in the auto will result in lower RPM than the 6th gear in the manual.
The higher the RPM, the higer fuel consumption (and lower mpg).
So yes, in case of the TSX, the manual is worse on gas.

 

It's not just the gears in the tranny that matter but also in the diff.
Acura should change the gearing in the MT to lower the RPMs at highway speeds to increase milage.

 

i think its hars to make a blanket statement that gearing alone will give better fuel economey.
just because you put in a taller gear ratio does not mean your fuel economey goes up.
there will become a point where the gears are too high and the engine will have to work too hard to maintain highway speeds while overcomming wind resistance.
im sure in this case the TSX would yield better MPG by raising the gear ratio a little.
i have a feeling that if you raise the ration very much it would be counterproductive.

 

Honda has this nack of keeping the ratio pretty close together (except in the TSX 1-2 shift that i hear a lot of you guys complain about). When I had the S2000, i wished that 6th gear would be a huge overdrive gear, but it wasn't. Keep 1-5 close... and 6th is strickly a cruising gear. Granted, this would force to downshift more often but that's part of the fun.

 

In general yes, but in the case of "performance" mt's (i.e. mt's being a performance option rather than a base function), including the TSX, this is not the case. The 6mt in the tsx is geared rather aggresively and hence the worse gas mileage.

There has been some debate on here about hondas choice for such a high ration 6th gear. Some feel we could have had aggressive gearing, and still get a tall overdrive 6th gear.

 

While the close 6th gears is not good for gas mileage, it allows for effortless highway cruising and passing. The engine is responsive event when crusing on 6th.

I'm still able to get around 30mpg with my 6MT if I don't drive with a lead foot and shift at the right time.

 

I drive very aggressively, and with a 50/50 mix of hwy and city I'm getting about 26mpg.

I find that aggressive driving in the TSX does not affect gas mileage as much as it would in other cars. Or maybe its all in my head

 

I get nearly double the mileage on the hwy than I do in the city.

 

I find aggressive driving does hurt mileage, compared to my current mpg figures. I used to get only 21-22 mpg, a lot of stop and go driving and agressive driving. Now that fuel cost is going up, I'm trying to drive as smoothly as possible. My navi says i'm still at 30mpg, so I will calculate it myself at the next fuelup to see if it's true or not.

I do notice no matter how agressive i drive I don't drop below 20mpg, which is pretty decent.

 

Dan, you gotta start shifting out of first gear in the city!

 

I paid for VTEC and damn it I'm gonna use it!

 

I see about 23 mpg on average. I drive in a "spirited" manner, and there are a couple of "items" on the car that aren't exactly stock when it comes to effecting fuel "economy." :devil:

 

The primary reason why manuals are more fuel efficient than Automatics is due to the fact that the autos require 10-12 horsepower just to turn them. Automatics are almost like an engine in themselves. Thus the inherant drag is actually sapping energy from the engine that could instead be used to turn the wheels. This is also why the 6sp is a tad faster than the auto because in addition to the lower gearing, you've a few more ponies going to the wheels.


I'm very pleased with my 6spd, I'm currently getting 30-31 mpg 60/40 with spirited driving. I don't baby the thing, I floor it pretty often...I mean, its a Honda 4 banger. Whats really nice is that my Civic EX SOHC vtec only got a few more mpg better (32-33mpg) on the same weekly commute !

 

true and the reason in mainly due to the fact that an AUTO has to turn a hydrolic pump that provides the pressure needed to actuate the bands and clutches in the tranny. also because the drive train is coupled indirectly through the use of trans fluid the engine is always turning faster than the transmission's input shaft. (except when the clutch in the torque convertor is engaged) but even in this case the pump still has to provide pressure to keep the clutches engaged.

 

auto has better mpg then manual on paper, but after observing the the forum, i do believe that manual does have better fuel economy than auto (but not like 15-20% on other cars)