I know that bmw etc have 6at standard. And our cars have 5at standard. But whats the real difference. Please include pro-con-other.

 

more gears = better gas mileage, better acceleration, probably some others as well

Mercedes has a 7 speed AT

 

more gears does not always mean better acceleration. I think it is mostly for luxury and mpg's. Luxury the car can shift more instead of holding gears longer. Mpg most have a highway gear that allows the rpms to stay low. It can back fire though. My friend has a gmc acadia with a 6 speed and the motor is so underpowered it rarely will stay in 6th gear on the freeway. My tl-s at 70 is right aroun 1950 rpms. I think a 6th gear in our car would not change mpg's much it would just make 3 and 4th into 3 gears slightly increasing topend acceleration.

for what is worth my evo is a 5speed and it owns the evo mr 6 speed it all aspects including mpg according to fueleconomy.gov also the sti has a 6 speed which effects it big time in the 1/4 mile. I can trap 120 in 4th while the sti is 5th at like 105. Different topic I guess. But more gears is not always better. Think about a car with 12 gears to get to 60 you would have shift into 6th.

 

If you want to compare 5at to 6at, different cars, the 6 speed will have a slight advantage with fuel econmy as the gears can be spaced accross a wider spectrum, but acceleration may be lost in the process as well since it takes time to switch gears.

If you are talking about only the TL, 5AT vs. 6MT, then in power, the 6 speed is superior, but in gas mileage terms, the 5AT is superior. In 6th gear, 80 MPH, the 6MT revs at 2750 while the 5AT runs at 2400 RPM's. I read here that the 5AT is geared for a 250 MPH top speed while the 6 speed is closer spaced and is rated for 210 top speed, but the motor cannot go that high.

 

closer gears means you can stay at an average lower rpm more (better gas, less engine "noise"), or an average higher rpm (better performance).

however, it starts backfiring when you need to be shifting so many times... more time not in any gear and more time where the transmission is slipping and screwing with your efficiency. not sure where the balance is.

yes, luxury cars often have more gears because they cost more, and they provide a more even/smooth acceleration.

(p.s., i bet you'll find the acadia has a more powerful engine as an option and they just didnt bother changing the gear ratios to compensate for the smaller engine. for example, 5th gear (top gear) is almost useless in the 4-cyl version of the tacoma, but is perfect for the V6.)

 

The primary purpose of more gear selections in a transmission is to allow closer (sometimes called "shorter" or "tighter") ratios between each gear, and the ability to save the final gear for a higher ratio to aid in fuel economy. Closer spaced gear ratios allow the engine to remain closer to its peak torque curve (assuming the driver knows what he's doing and the transmission's ECU logic is so programmed). Wider ratios create a broader RPM difference as each shift to the next higher is made. This is an unfavorable condition for hard acceleration.

 

The number of gears you need is dependent on your driving style. Nothing wrong with 5 speeds if all you do is cruise the highway, take the kids to school and go shopping. If you do that, 6 speeds can even be too many because you are shifting all the time. My S2000 with 6mt was annoying to my wife at times because the gear ratios were too close and she had to shift too often. For performance driving or track days, that is when you actually need 6 speeds and will appreciate the ability to keep the engine in the "power band".

 

Lexus have an 8-speed automatic. I haven't read much about it other than that I recall Car and Driver had some positive comments.

Every car is different in what sort of gearing is needed. I used to have a 1997 Accord EX coupe with a 5MT that would have benefited from a 6MT. Once I hit about 75 to 80 it needed a higher gear that it didn't have. The TL seems perfectly fine with the 6MT, whereas Ms1995hoo's 2003 RSX Type-S could use a 7MT or maybe even an 8MT if such a thing existed. At 80 mph she's turning over 3,500 rpm and the noise really picks up. The only 7MT I've ever seen, however, was on a tour bus in Russia (yes, it was a floor-mounted conventional manual transmission). That RSX can really be quite loud once you get above about 75 mph. Thus, noise is another consideration when looking at the number of gears. I think the size of the engine is relevant as well—the smaller engine 1.8-litre engine in the RSX needs to work harder than the TL's 3.2-litre V-6, so it would benefit from another cog.

I know Ferrari and perhaps BMW have come out with paddle-shifted 7MTs similar in overall concept to what F1 cars use, but I'm referring to an MT with a conventional H-gate.

 

WHAT??? Have you even looked at the EPA average on the two cars? The 6MT beats out the 5AT! All the people on the forums that are posting better fuel economy ratings are people with 6MTs not 5MTs.

 

But is this due to the way people drive or due to the transmission? I've found that MT drivers (in any car) tend to be a lot more aware than AT drivers not only of how to shift (that's a given) but also of when to shift and how to drive a car for optimum performance, whether "performance" means acceleration or fuel economy. Automatic transmission drivers in the DC area tend to drive me nuts because so many of them don't have a clue how to accelerate, given that the transmission does the shifting for them. They accelerate too damn slowly and I have to be prepared to hit the clutch again. Everyone I know who drives an MT has commented on the same phenomenon—we accelerate differently because we know when we will need to shift and our driving style is based in part on that.

Based on that, it's not hard to consider how someone driving an MT who wants to save fuel will use a higher gear if possible, or select a slightly slower speed so as to make it feasible to use a lower gear without wasting gas due to revving higher than needed, etc. The AT driver doesn't generally think about any of these things and just sets his speed to whatever is comfortable or to whatever he thinks will save him gas.

(Yes, of course I'm over-generalizing, but as a general rule, the MT driver is more in tune with his car than the average AT driver, and I'm not referring to the types of people who read this sort of forum, either—I mean your average driver out on the street.)

 

^^^ I have to agree.

Generally MT vehicles are more fuel efficiant (or worse, depending on how you look at it) - because you can force the car into a lower gear, and it will not kick down unintentionally if not needed.

The same works the opposite though. Since you control the shifting, you can also hold it higher into the gears - ruining any chance of decent MPG's.

Either way, when it comes to MT vs AT - on paper, I'm jealous. Stuck in rush hour every day - you can keep your clutches.

 

^^^ love your avtaar.....i bang my head on the computer couple times a day.....lolz....

back to the topic.....the Lexus IS-F has 8MT......as mentioned the fuel eff depends on how you drive....MT will give you more MPG if you shift early and dont have a heavy foot on the gas.....and if you pop the clutch many times, u just killed MPG......

more gears have 1 disadvantage that I read (specific to Lexus IS-F) is you might not get the desired acceleration you want......as in if u need acceleration and you are on 5th gear in a TL.....you might drop down to 3rd and zoom off......compare to.....if you are on 8th gear and you need acceleration.....5th might give slightly more than you need and 6th might give slightly less.....and you would keep toggling between gears......

btw by the time you hit 8th gear....you will hit traffic and have to shift back to 4th or 3th.....

 

Funny, I've lived in the DC area all my life (not counting while I was away at college and law school) and I've never owned an automatic-shift car. The clutch doesn't bother me in the least, and I find that on the rare occasions when I have driven an automatic (Acura loaner car, rental car when I travel, or I drive someone else's car) I have a hard time regulating the automatic—I unintentionally kick it down at inconvenient times because I'm not used to it.

Guess it's all a matter of what you're used to driving.

 

very true.

but thats why lexus engineered those shifts to be that fast. So it would be the same as another standard car shifting down. instead it shifts down 3 gears.

im biased because i drive a STi, coming from the TL 5AT, theres gas mileage gains with the sti. surprisingly.

 

The biggest driving factor behind picking the number of gears is the width of the power band. A lot of the muscle cars from the 60s and 70s had 3 speed automatic transmissions. There was torque all over the place so it worked out.

We all know that torque all over the place is the opposite of the Honda ethos. A quick revving engine with a peaky torque curve benefits the most from a higher number of gears because the transmission has more opportunity to put the RPMs into the meat of the power band.

Semis produce amazingly huge torque numbers (the bigger engines put out in neighborhood of 1,500 ft-lbs!!!) but it's only available from about 1,500 to the 2,500 redline. Consequently they have double gearboxes with 12 to 24 total gears (think of a 10 speed bike with 2 gears on the pedals and 5 on the back wheel).

When you're talking about a car like the LS with its 8at, this is done mainly to keep the RPMs low and the engine smooth and quiet. There is plenty of available torque out of that engine but the engineers (correctly) figured that the people buying that car were not going to be hitting WOT to often and would rather have a smooth and quiet ride. It helps that they've got the financial headroom to build a transmission that is capable of shifting in a nearly imperceptible manner. My dad has that car and you do not feel the car shifting at all under normal driving conditions.

So in the end, the reason for picking a higher number of gears comes down to the desire to have the engine be in a particular rev range. For the S2000, that range is up near the tippy top of the tach. For the LS, it's down at the bottom.

 

on paper, the 5AT revs lower at the same speeds, but getting to those speeds is where the 6MT is superior, the lower weight and quicker acceleration help.

 

What's the final gear ratio in high gear for both types of TL transmissions? If they are different, maybe that's why the difference in mpg between to two types.

For the best economy, I would think car mfgrs would use a higher gear ratio for crusing above 70 mph..
2000 rpm at 70 mph just seems like too many rpms for best economy.
True, acceleration would be non-existent with a higher final gear ratio.

 

AT = 0.48 (5th)
MT = 0.77 (6th)

Don't know if this helps, but there are the numbers

 

Word.

 

He asked for the final gear ratio which would normally mean the highest gear in the transmission multiplied by the final drive ratio.

So for the automatic, that would be .48 x 4.43 for a final gear ratio of 2.126. For the manual, the figure would be .77 x 3.29 = 2.533.

As you can see the manual, even thought it has a much higher final drive ratio, delivers a significantly lower final gear ratio than does the automatic. And it is the same for the rest of the forward gears. While this might lead many to think that with the engine turning faster in a manual TL in 6th gear it should get a lower MPG reading. But what is not considered when arriving at this assessment is the fact that the automatic "hunts". Slight increases in engine load (hills, throttle input for passing, etc.) result in the transmission downshifting to compensate. With the manual, the driver has total control over this and need only shift to a lower gear when HE deems it necessary.

 

SS mode FTW!

 

Yes, that would remove the hunting aspect.

I do have a question about this, if you don't mind. My other TL is an '05 automatic and is the wife's ride. She never uses the SS mode, preferring to just leave it in Drive and let it do its thing. For those who do use the SS mode either frequently, or mostly, was there a mental training period you had to go through to remember to upshift? With a manual, this is just so obvious but for an automatic in SS mode, it's still an automatic which means no manually operated clutch.

Just curious.

 

Nicely said. my dads logging truck has 18 gears. its cool, theres 9 physical positions on the stick, then a toggle switch on the shifter under your thumb to switch to the higher gears, then you re-use those same 9 positions. talk about a lot of shifting! ...btw, i think its a ford if your curious.

 

Personally for me, I haven't driven in SS that much, but in the few times I have, will upshift when the motor starts to get a little louder a 3K. But if you don't know your in SS and don't know what it is or how to use it, upshifting is unlikley. Personally, I think SS is a feature to attract buyers, it doesn't get used that much, but the flappy paddle ones will...

 

Yeah, for me, a "pretend-a-manual" automatic tranny would strain my "normal" driving technique quite a bit, I'm afraid. It would really be a learning process for me. Perhaps if automatics had a clutch pedal (even if it didn't really operate a genuine clutch assembly, the learning would feel more natural.

I well remember a model of car (think it was a DeSoto, but I'm not sure) that a friend had in high school. This car had a three-speed transmission on the tree (column shift for those who don't know what this means). There was a clutch as one might expect. But the transmission was a fluid coupling type and acted like an automatic. So he could stop at a light, put the car in first gear, then let the clutch out completely. Really strange design and nothing I would ever want.

 

I also have both TLs, and on long road trips- both have made the Northern VA to Southwest FL trek at least twice- the auto gets roughly 1mpg better mileage, speed for speed. The 6spd's best came in at 31.2mpg, averaging 71mph for the tank (that's calculated, not MID), and the auto's best at 32.1mpg averaging 72mph for the tank. Typical cruise speeds are 74-77mph, so the lower speed average accounts for pee-stops with the kids.

On road trips, I consistently see this 1mpg difference, and it's largely due to the lower RPM on the auto (2000 shows 60mph on the 6spd, 2000 shows 67mph on the auto). I don't see hardly any hunting either, but I will lift ever so slightly to prevent the torque converter from unlocking until it really needs to.

Oh, and you *need* the ATLP J-pipe for the 6spd car. You must trust me on this.

 

I get just the reverse numbers (calculated just like you). When both cars had their stock OEM grand touring tires (the '05 had the Michelins and the '04 had the EL42's), my '04 managed a best of 33.94 heading south on vacation with A/C on the entire leg. The '04 was coming in slightly over 32.

I checked out the numbers on the J-pipe and they are indeed impressive. Does it work this well and give these good numbers with the stock exhaust, too?

 

I didn't do a dyno before or after, but-

1. The butt-dyno definitely feels the midrange torque. Top end, I can't tell- I don't spend much time above 6000rpm anyway.
2. It would appear that I'm getting a solid 1-1.5mpg gain since installing it.

P.S. I can't even think about touching 34mpg unless I average 60mph. You just don't go that slow when taking a wife and two kids to Disney World or Grandma's.

 

The day I got that mileage (early September '05) was like this.

We got a much later start than normal because we were watching a hurricane develop in the area where we vacation. So instead of heading out at 4:20 am Sunday morning, we gassed up and hit the road a few minutes after 12 noon. Temperature was 86 degrees so the A/C was running the entire time. Car was loaded for a week's vacation and just the wife and I were aboard. For the first 50 miles, our average speed was around 62 MPH. The next 130 miles averaged 73 MPH. And the last 80 miles to our first stop (food and fuel) averaged around 78 MPH. All of this was in moderately heavy traffic that moved.

When I do a mileage check, I always try to do the fillups at a pump that is at roughly the same angle so the fill is not affected by a difference angle. I also stop at the first auto-shutoff, then add to the nearest 5 cents. This gives me the best chance to get an accurate fill for the check. Of course, pump measurements can be off, but I also look for newer stations - more because of the in-ground tank conditions. And I burn the same gas.

On that first leg of the trip that day, I got 33.94 MPG. As I said, I still had the stock EL42's on my TL. The following spring, I had Michelin Pilot Sport A/S tires put on the wheels and immediately noticed the difference in rolling resistance (as in backing out of my garage). With these tires, I have not been able to get much past 32 MPG on a road trip. In town mileage is lower as well with them.

 

Interesting. Both of my TLs have the Pilot Sports. How was the handling on the EL42s?

 

Passable, but not by any stretch conducive to more enthusiastic driving. They also tend to hydroplane quite a bit but not so much with the TL as with my former car; a 2002 Altima SE which hydroplaned like crazy with the EL42's.

The Pilot Sports A/S's made a marked improvement in the TL's handling and compliments the manual's suspension quite nicely. Still next time around I am considering the B.F. Goodrich g-Force Super Sport A/S tires. They seem to get good marks and from the design of the tread, I would bet they are a good compromise between a handling and a grand touring tire.

 

To all you who are getting more than 30mpg, Can I assume these trips you mention consists of flat condition driving?
The best I have gotten is about 30.5 mpg on trips to Las Vegas and back (some pretty good sized mountain ranges to go over). And with traffic the way it is on Interstate 15, it's pretty hard to average above 70 mph.
My MID mileage indicator has never even been close...consistently about 3 mpg higher than actual. At one point during the trip (after about 50 or so miles) it indicated 38 mpg at 60 mph.
226 miles for the one-way trip, MID indicted 34 mpg, put in 7.5 gallons which is only a little over 30 mpg actual.

I'd sure like to see lower rpm's at 70 mph without having to change wheel/tire sizes..
Come on Acura, give us a true cruising gear

 

My tl-s reads just under 2k at 70. Seems like a nice highway gear in the tl-s

 

The first leg of a vacation trip I wrote about covered several highways here in Virginia, from the piedmont (base of the mountains) to the east-central part of both Virginia and North Carolina. The first 50 miles of my trip was on 4-lane highways with speed limits of 55 MPH in a Virginia country setting. That means mild hills and curves. The next combined 210 miles was on a major interstate highway, which happens to be the most traveled interstart in the country - I95. Mostly it is relatively flat except for the 50 miles or so that I was on it above Richmond.

So yes, the highway terrain is agreeable to highway travel and decent fuel economy. But I would bet that my 33.94 MPG under the conditions I outlined is a very good average. I was quite pleased. For the record, my average for the entire trip, which includes a highly desirable vacation destination for a week plus the trip home, was a little over 30 MPG. And I was incorporating no special fuel-saving measures during any part of the trip.

 

As for final gearing, this is almost entirely a factor of engine torque coupled with fuel economy. My '04 manual TL's engine turns 2000 RPM at 60 MPH in 6th gear. My wife's '05 automatic turns approximately 1725 RPM at the same speed in 5th gear. As soon as I tip into the throttle in her '05 while on the road, the transmission downshifts. If the engine was producing more torque and had the same gearing, the ECU would allow a little more throttle before the downshift.

It's all in the numbers.

 

Are you sure it's downshifting? Mine unlocks the converter, although not nearly as sensitive to the throttle as you make yours out to be. For instance, I can run from here to Winchester (66W to 81N) and the converter will come unlocked maybe once to maintain speed- 70-75mph the whole way.

 

You're probably correct about unlocking the torque converter as opposed to an actually downshift. Engine speed definitely increases right away when this happens, but I'll chalk it up to my ignorance regarding automatic transmissions.

And I should not have said "as soon as I tip into the throttle". It's more along the lines of a little more than a tip. I do know that when passing with her car on a 55 MPH 2-lane road, the tranny downshifts pretty smartly and the sensation of acceleration is very good.. not mushy at all.

As for going from here to Winchester, I suspect her car is much like yours. I'll know today because we're going to Front Royal early this afternoon and will be taking 66 and most likely, her car.

Hey. Next time you go up in that area, save your appetite and hit Melting Pot Pizza in Front Royal for the best pizza you can imagine. Nothing like a Pizza Hut or Dominoes pie. It doesn't even look the same. Best I've had.

 

Just got back a short while ago from Front Royal (yes, a trip to Melting Pot Pizza). We took my wife's '05 automatic TL and not once did it hunt while traveling on 66. I set the cruise to 71 MPH and all was well.

 

Good to know. Thanks for the pizza tip!

All this talk about mileage auto vs. manual, I should point out-

In mixed driving, city & highway, I *always* get better mileage in the manual. I control the shifts, am not afraid to run 45 in 6th if the road grade allows, and upshift at 2200-2400rpm if I'm "lollygagging." The best I can do in the auto on my work commute is about 22mpg, whereas I'm getting 24-25 in the manual.

 

My wife averages over 26 MPG in her all-around driving with her '05 automatic (part time work at a country church and everything else she does). And she is not light on the throttle plus she uses her A/C more than I do.