Corolla v Civic v Hyundai/Nissan moeds

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Current generation Honda Civic.
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Elmo P. Shagnasty wrote:

Clay
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Nope. Look again.
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Elmo P. Shagnasty wrote:

Fueleconomy.gov
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Not to sound condescending or anything, but I am glad you chimed in, because on further reading, I thought it should be pointed out that a major factor in automatics traditionally getting worse MPG is the torque converter. The TC represents a "fluid coupling," whereas the manual tranny's clutch etc. are a mechanical linkage. Energy transmission losses are greater with the liquid linkage. As many of the pros here know. (I am just an amateur who works on her own car and reads like crazy to understand it.)
But this has changed somewhat with the advent of the "lock up torque converter."
Optimal gearing is still said to be a factor, though. Several other factors are said to play significant roles, as well. So my post did not do justice to why older automatic trannies were less efficient than manual trannies.

Sure. www.fueleconomy.gov. Just sort of randomly, based on checking this a few times in the last several years, and using only the same engine size for a given model:
2007 Civic, same engine size, both five forward speeds: Manual = 26 MPG city, 34 MPG highway Auto = 25, 36
2007 Subaru Impreza (an all-wheel drive vehicle) Manual (5-speed) = 19, 26 Auto (4-speed) = 20, 25
2007 Nissan Sentra Manual (6-speed) = 24, 31 Auto (variable gear) = 25, 33
2007 Hyundai Elantra Manual (5-speed) = 24, 33 Auto (4-speed) = 25, 33
2007 Kia Rio Manual (5-speed) = 27, 32 Auto (4-speed) = 25, 35
From this survey, I think we could argue that newer automatic trannies seem to do better at highway speeds, even though it often has fewer gears. The lock up converter (used only at higher speeds) is the first area I would explore to explain most of this higher efficiency. I see the lockup converter started gaining in popularity around the late 1970s but ISTM only recently did all models start having them. I see the 1995 versions of the cars above never saw the autos beating the manuals for miles per gallon. Granted other improvements may have been implemented, like continuously variable transmissions (CVT).
The Sentra is interesting, since for the two versions I compared, the big difference is the variable gearing in the auto. It's the only model that beat the manual version in both city and highway.
Toyota OTOH seems to consistently have no models where the auto does better than the manual under city or highway conditions.
Again, just an amateur here.
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My Chrysler 4 sp automatic, which came out in the early 90s, has lockup on the top 3 gears. In effect it has 7 gears. The fuel mileage is excellent.
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"lockup" doesn't change gear ratios,it just eliminates torque converter slippage. it "locks" the input turbine to the output turbine.
No "7 gears".
"Overdrive" would be "extra" gears.
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Jim Yanik
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Jim Yanik wrote:

When he wrote "in effect" he was probably right. Unless the RPM at lockup happens to match between one or more of those combinations, you get seven different "ratios" of crankshaft to ouput shaft speed, even though it doesn't happen because of gear ratios changing.
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nope. wrongo. when the converter locks up,the crank RPM equals the converter output RPM,because they are -locked together-. No slippage.
after that,it's all gear ratios determining output shaft RPMs. fixed ratios.
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Jim Yanik wrote:

Are you deliberately misunderstanding us? Nobody claimed an overdrive type shaft speed ratio. What is being said is that when the lockup engages, you do in fact get the geared ratio - which you *weren't* effectively getting with the converter unlocked. So for each gear in which the lockup works, you have two different shaft speed ratios: one with the lock off and one with the lock on. The *effect* is the same as having seven gear ratios, with *none* of them being an overdrive. I don't know how much clear I can make it...
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It's still not any "effective gear ratio".It's just slippage.Wasted energy.
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Jim Yanik
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Jim Yanik wrote:

Whatever you have to say. Usenet never changes...
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So my slipping clutch in my old mustang 3 on the floor effectively meant I had a six on the floor kinda maybe? Or did I miss a imaginary gear or 2?

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From my reading, the typical auto tranny's lockup does not fully engage until cruising at speeds upwards of 40 mph. At 40 mph, it is probably in 3rd or 4th gear. At lower speeds, the lockup is disengaged. But the gear should alway be lower at lower speeds, too. So I am not sure that I buy Josh's characterization of doubling the top three gears to yield effectively seven gears on a 4-speed automatic tranny.
On the other hand, I see that "partial lockup" is possible and occurs under many conditions, too. This is per the 95-97 Civic's description at http://media.honda.co.uk/car/owner/media/manuals/CivicManual/pdf/14-34.pdf . Partial lockup has to be better than no lockup, as far as overall fuel efficiency is concerned.
So I would say it is not exactly two gears for one that lockup on/off gives. It's more that lockup is often active in degrees, being neither fully on nor fully off. When it is "on" even partly, I expect it usually helps fuel efficiency compared to no lockup at all.
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<"mjc13<REMOVETHIS> >

slippage would be an infinite number of "gears".
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In this context, where I think Josh was arguing the lockup feature increases the effective number of gears and so increases engine efficiency, I would not put it this way. The slippage is arguably infinite gears but not in a way that improves efficiency the way direct mechanical linkage (= lockup) to infinite gears would.
To split hairs.
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Elle wrote:

Agreed. I have no idea if the transmission cited engages the lockup at low speeds or not. I could see it helping at 30MPH on level ground in third, though...
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Elle wrote:

Just a short anecdote here...
I'm not sure what manufacturer introduced "lock up converters," but Studebaker began using its self designed automatic featuring a lock up converter for the 1950 model year.
My 1955 President, a hefty 4,200 lb sedan with 259 V8/DG-250 tranny achieved 21/28 mpg in real time road tests in that era. Not bad for a 4 bbl carb, auto and pretty good performance. My uncle used to really rub it in to Chevy/Ford owners...
In a lot of ways, we really haven't advanced much farther.
JT
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Did you have a CAT on that Stude and run ethanol tainted gas?
wrote

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Elle wrote

Bravo. I read Wikipedia a few hours ago and I believe it confirms Studebaker was first c. 1949.

They did MPG tests back then? What is the history of fuel economy becoming important to car manufacturers?
Elle Who pumped gasoline as a summer job when it was 59 cents a gallon.
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