MPG: Automatic vs. Manual Transmission

honda
cr-v

#1

I have purchased my last several cars with manual transmission. The reasons were twofold: 1. It got better gas mileage than its automatic equivalent. 2. Most kids who steal cars have no idea how to drive one. Lately reason number one no longer seems to hold true and I’m wondering why that has changed.


#2

Automatic transmissions are more efficient than they used to be, and the gearing for the manual and automatic are probably not the same.


#3
I suspect you will find that manuals are still generally more efficient that autos but not as much as they were.

#4

I’ve always driven manual transmission cars – they are more fun and offer better control. Increased mileage was a side benefit.

New shiftable automatics with 7+ speeds and locking torque converters are giving manuals a run for the money. MB, BMW, Audi and others offer dual clutch “semi-automatic” transmissions that shift in 100ms, blip the throttle and rev-match down shifts. They also allow car manufacturers to meet ever increasing mileage and emission requirements.

Twotone


#5

I can give you reason # 3 to stick to manuals - they are mechanically much simpler than automatics and, as compared to automatics, rarely have severe internal issues that require very expensive rebuilding. You replace the clutch once in a while but I’d take that over automatic trans troubles any time.

If manuals were commonly found in minivans I’d never own another automatic.

The answers to why autos are comparable on MPG have been given.


#6

I think U.S. auto manufacturers wanted to phase out manual transmissions starting back in the mid 1950’s. In those days we had the 3 speed manual transmission with the shift on the steering column. The shift linkages on many cars made shifting difficult. I had a 1947 Pontiac that was very smooth shifting as was the 1954 Buick that I owned. On the other hand, my 1955 Pontiac and 1965 Rambler shift linkages were terrible. There were conversion kits to convert the column shift to a smoother shifting floor shift. The automatic transmissions also improved in acceleration about this time period. The Chrysler Torqueflite did very well in drag races against a similar car equipped with a manual transmission. There was a company that sold the B & W Hydrostick–a beefed up GM 4 speed hydramatic to hot rodders back in the early 1960’s. Also, back in this time period, the manual transmission wasn’t exactly trouble free. Many of the 3 speed transmissions that were standard equipment were designed in the 1930’s and didn’t stand up well to the more powerful engines of the late 1950’s.

The heavy duty 4 speed manual transmissions of this time period were a different story. These transmissions were designed for drag racing. However, the top gear was direct drive and the final gearing in the rear axle was numerically high which wasn’t the best for economy.

Many of the automatic transmissions from the 1950’s were 2 speed units and the manual transmission easily got better economy. Today’s five and six speed transmissions with the lock up torque converter (actually, this isn’t recent–the 1951 Studebaker automatic had a lock up converter) and the CVT transmissions really give the manual transmission stiff competition in the gas mileage department and offer good acceleration as well.


#7

Auto mfrs submit fuel mileages to the EPA as they see fit with the EPA doing spot checks. There is no problem with submitting numbers less than what really happens if the corporate goal is met. EPA mileages, like always can be taken with some skepticism. It may be possible that some mfrs offer a manual trans for those that insist but want to steer people to automatics as there is more profit with an automatic.

Personally, I belive that a manual always gets better fuel mileage than an automatic. Note that the Chevrolet Cobalt XFE with a highway number of 37 has a manual trans.


#8

Lately reason number one no longer seems to hold true (better gas mileage) and I’m wondering why that has changed.

It is related to locking torque converters and shift points.

Manual transmissions have a direct connection between the engine and the wheels, which gave them a fuel economy edge over torque converters in older cars which didn’t have that direct connection. Today’s automatic transmissions have torque converters that lock, and create the same direct connection.

Then there are the shift points. Today’s automatic transmissions are programmed to shift at lower RPM limits, which makes them more fuel efficient than they used to be. You can do the same thing with a manual transmission, but most people don’t. Most people who drive manual transmissions don’t shift at RPM points that would maximize fuel economy, but it can be done.

Since those are your only two reasons for driving cars with manual transmissions, the advantage might be small enough that it isn’t worth it anymore. Your second reason (theft prevention) can be mitigated with a good alarm system and LoJack (or something like it).

Personally, I have additional reasons for driving a car with a manual transmission:

  1. Manual transmissions are cheaper to own.

  2. Manual transmissions are cheaper to maintain.

  3. Manual transmissions are cheaper to repair.

  4. I think manual transmissions are more fun.

  5. I am a professional driver (although I have changed careers). It is a point of professional pride that I can drive a wide variety of vehicles that the average amateur isn’t capable of driving.


#9

If you have a car worth stealing, it’s not going to be a kid stealing it, it’s going to be someone who knows how to drive stick. If they have time to try to steal your car and get frustrated because of the manual transmission, they have time to delete your windshield and key your paintjob.


#10

"Lately reason number one no longer seems to hold true and I’m wondering why that has changed."
Because computers do a better job of shifting then people.


#11

Let us not forget the factor of the newer CVTs.
Instead of being equal to a manual shift car in terms of gas mileage, a driver with a CVT can actually achieve better gas mileage than even a skilled manual shift driver.

Case in point is the new Subaru Outback. The gas mileage figures for the 4-cylinder model are:
Manual trans–19 mpg city/27 mpg highway
CVT–22 mpg city/29 mpg highway

Most drivers of the Outback CVT models routinely report 30 mpg on the highway, with many reporting 33 mpg on long highway trips–which is pretty darned good for a boxy vehicle weighing over 3,500 lbs.

While I would be reluctant to own one of these vehicles with a CVT, due to lack of long-term reliability statistics, the fact remains that they can achieve better gas mileage on a day-to-day basis than would be possible with a manual trans.


#12

This is a little off the subject but it involves manual vs automatic transmissions. When I was a young teenager the prevailing thought in my town was that automatic transmissions were inferior to manual transmissions. This was in the mid-60’s when most teenagers drove cars and trucks from the 40’s and 50’s. Almost all of my friends believed that automatic transmissions could not even spin a tire. In the spring of 66’ I proved them wrong.

My junior prom was fast approaching and I asked my dad if I could borrow one of his cars to the dance. He had a 59’ Plymouth stationwagon, a 59’ Corvette and a 65’ Pontiac 2+2. He turned thumbs down on the Corvette and I turned thumbs down on the Plymouth. He loaned me the 2+2 on the condition that I would drive straight there and back (4 blocks). I agreed. When I got to the dance my friends asked me to “pop the hood”. I did and I saw 3 “deuces” on a massive 421 engine under the hood. When the dance ended…3 of my friends piled into the car with me. We got about a block away and I pulled over to the curb. The streets were deserted so I gunned the engine in drive and the right rear wheel went up in smoke. I went about a block with my tire smoking all the way and leaving a narrow black line on the street.

My friends passed the word along the next day and the old automatic transmission fable was history in our little town at least. I ran that 2+2 on an engine dynometer a few years later at our new Vo-Tech school and it registered nearly 500hp. I guess I could have made it another block with a smoking rear tire but it was not to be. I traded that 2+2 for a mint 57’ Chevy Bel-Air hardtop shortly after that.


#13
  1. automatic transmission technology has come a long, long way these past few dacades. And the trannys themselves operate with lower inherant losses.

  2. the overwhelming majority of cars stolen are hot wired, and not by pros. Doing so in a timeframe short enough to keep from getting caught requires some minimal knowledge of cars. I’d bet that the overwhelming majority of car thieves know how to drive a manual…and probably know more about how cars work than most of the owners they stole the cars from.


#14

#2 is a very important reason to me too.
I’ve owned four manuals and two automatics. The automatics were both stolen.

  1. Manuals generally have better low speed acceleration. Especially with small-engined economy cars.
    The torque converter saps some power when it’s not locked up.

#15

Don’t count on a CVT transmission lasting as long as a manual gearbox. Possibly you might save a little gas but will pay it all out and more when the CVT goes south.


#16

I don’t know about the gas mileage issue, but my ADD riddled brain quickly bores when I drive an automatic. Stick shifts seem to be harder and harder to come by, and I think that’s sad.

Most of the newer autos are pretty good, but some of the older ones I’ve owned (particularly a 2.8 liter Corsica with 3-speed auto. Awful drivetrain!) frustrated the hell out of me.

Last week I got a lightly used Nissan Versa S w/1.8 liter engine and a six-speed manual. It weighs about 2,700 lbs. and goes like a bat out of hell! I’m really enjoying it. Pittsburgh has a lot of hilly terrain and my Versa accelerates fairly smartly, even somewhat uphill, to 60 MPH or so without having to flog it. My '95 Civic (4-speed auto) couldn’t get out of it’s own way at times, and some highway merge points were pretty scary, in spite of it being lighter than the Versa and having a similar engine.


#17

Automatics often have a higher top gear than the manual versions do, mostly because people complain about having to downshift for every hill if they are geared this way. Especially with sport vehicles where drivers think “torque” means being able to pass without downshifting so the car makers give them cars that are permanently in a passing gear.
This may have something to do with some automatics getting better gas mileage than their manual counterpart.

On my car, a Toyota Yaris, the manual is rated higher by the EPA, but barely. 29/35 verses 29/36. I own the manual version and I seldom get less than 40 mpg, my last fillup was 44.5 mpg so a lot depends on how the vehicle is driven.


#18

Wha Who ?-“Don’t count on a CVT transmission lasting as long as a manual gearbox. Possibly you might save a little gas but will pay it all out and more when the CVT goes south.”

I think that “maybe” true but; Subaru claims their’s will last the life of the car with little or no service. You can’t say that about a clutch. But then, I’m suspicious of any claim made by the person who’s making the profit. So, I’ll agree with you all, for now :=)


#19

when the transmission dies, that’s the life of the car for most people