Automatic Transmission With Higher MPG Than Manual?

I noticed that some automatic transmissions actually have EPA MPG ratings than the same car with a manual transmission. I assumed that this meant that this meant that automatic transmission technology had actually improved to the point that it was actually more efficient than some manual transmissions.

But I noticed that Consumer Reports rates the Honda Fit with a higher MPG for the manual than the automatic (33M/30A), while the EPA gives the nod to the automatic (29M/31A).

What’s the Straight Dope?

Could have to do with the shift points. Most automatics are biased towards economy. Manuals have shift lights and if you shift when the light comes on, you get better millage. If you shift sooner, you may sacrifice performance for economy. The automatic forces that bias.

I have little respect for CR, but their tests may be more reflective of the way people drive.

Also, a 6 or 7 speed automatic or an EVT will likely give better gas mileage than a 4 or 5 speed manual transmission. It’ll depends on the particular transmission and how they are tuned. But there are cars out there that will get higher numbers on the new federal MPG test with an automatic. Whether those numbers hold up in real world driving is a separate question.

All things being equal, manuals still have a slight efficiency advantage. But automatics have gotten much, much better with things like lockup torque converters and electronic controls and so this efficiency advantage has dwindled to near nothing. The cost and reliability advantages have also dwindled to being near-negligible. So the only really compelling reason to buy manuals these days is because they’re fun to drive and so car makers gear the manual transmissions lower than the automatic equivalents which give them peppier acceleration (and make them easier to get into gear) but slightly worse mileage.

As for the discrepancy between the CR and EPA numbers, there is a 4 speed and a 5 speed automatic. The EPA rates the 4 speed and the manual the same, with the 5 speed auto slightly better. Could it be that the EPA numbers you’re mentioning is the 5 speed auto vs. the 5 speed manual whereas CR is looking at the 4-speed auto vs. the 5 speed manual?

I’m pretty sure this explains it.

CR rated the Fit Standard with the automatic transmission and the Fit Sport with the manual transmission. I don’t see any reference to a 4-speed transmission. The EPA numbers for the manual are identical on both the Fit and Fit Sport, but the numbers are slightly lower for the Fit Sport with the automatic, but CR didn’t test this model.

Here is the CR review of the Fit:

But all things are not equal.

Theoretically, manuals could still give better efficiency than automatics. For a highly skilled driver. But most drivers on the road are not highly skilled. Even if they were paying attention to their transmission, instead of their latte or their cellphone conversation. So the real-world performance of manuals is generally worse than the automakers/EPA/Consumers Reports figures.

Automatics, however, are controlled by computers nowadays, so they generally perform pretty close to the quoted figures, with little deterioration in practice (unless the car is in great need of a tune-up).

So in the real world of daily driving, modern automatics probably are extremely close to manuals in efficiency – possibly even better in many cases.

Since this question seems to be sufficiently answered. Can I ask a related question? If manuals have no major fuel efficiency gain over automatics, why do you see so few automatics in Europe and UK?

There are also different numbers of gears that could be accounted for. For example the new Fiesta has the “standard” 5-speed manual (lower EPA estimate), and the optional 6-speed automatic (dual clutch, a bit different than the typical automatic).

This quoted for emphasis. The computer is generally better than a typical driver.

Because automatics are high tech electronically controlled devices and manuals are nuts and bolts type hardware. Manuals are much cheaper to produce.

Well, for one thing automatics are far more common in Europe than they once were and true manuals are starting to disappear from some higher end models. But manuals can still have the economy advantage if they’re geared for it, especially on cheaper cars where the really high-tech automatics aren’t offered. Of course a lot of people over there just prefer them, especially since manual transmission cars are such a tradition and practically everyone can drive them.

I’m sure this is true for some drivers (I can think of some family members of mine), but any reasonably competent driver should be able to get pretty close to optimum efficiency on a regular old 5-speed manual. But I think that really becomes true when you get transmissions with more and more gears, since the gear ratios are just so close together it’s harder for a human driver to really get a feel for them. So as the trend goes towards more and more gears, manual transmissions are going to get left behind for good.

I get 37/38 on the highway with a saturn 4 speed automatic. Unlike a manual transmission, the engine RPM isn’t lowered and raised through the gears. It’s just lowered as the car accelerates. Combine that with a narrow band of engine RPM efficiency and automatics do well.

Automatics often have a significantly taller overdrive ratio than the manual offered in the same vehicle. (Ford trucks, I’m looking at you).

This allows great freeway fuel economy when lightly loaded, and reasonable acceleration when the torque converter unlocks. The same OD ratio in a manual will seem totally gutless, requiring frequent down shifting, which many drivers won’t do, so a lower OD ratio is spec’d as a compromise.

While manufacturers have been cited for reverting to a special economy or low emission mode when the EPA test protocol is detected, they still optomize shiftpoints and similar parameters to obtain the best EPA numbers. I have even seen silly choices in manual transmission gear ratio spacing (Ford again, the ZF-6) that I can only guess put the rpm in the sweet spot for EPA testing. This is why the CR numbers may differ quite a bit from the EPA numbers.

Note I am picking on Ford because I know them well. I don’t think they are any more guilty than other makers in this regard.

As the high tech auto trans find their way into more cars, it’s death for the manual trans. Forget it. I’m calling it over except for the lower tier cars… for now.

Used to be there was so much waste in an auto trans that a manual would just zip off the line with its short first gear and even in mundane driving would zip ahead of auto trans cars.

My car has a 6-speed manual, and it also comes with a 7-speed automatic. On paper, the manual is .01 sec faster. Ain’t no way in hell you can beat the 7-speed automatic over and over. Fuel economy is dead even. In the real world, the 7-speed is more efficient and will win 80% of all drag races. To hang, the manual has to burn up its clutch with 4600 RPM clutch drops.

Cripes… they even have rev matching (GTR) and double-clutching in them automatics. Some of them shift so ridiculously fast that it isn’t fair.


I have been trying to figure out all the different transmission technologies using Wikipedia but the variety of technologies out there is quite bewildering even before you start looking CVT transmissions and try to figure out the differences between the different companies implementation.

I’m interested, since I want to drive a car with good fuel efficiency, but my left knee isn’t so good, so I don’t think I’ll be driving a car with a conventional manual clutch anymore.

I own a manual Fit, and can tell you that the primary reason that the mileage is lower than the automatic is that the final drive is rather short. At highway speeds of 110-115km/h the engine’s ticking over at nearly 4000rpm. Presumably someone at Honda thinks that North American drivers are too stupid to downshift if they want to accelerate at highway speeds, and so we don’t get a proper overdrive for top gear.

That, and that little motor just begs to be revved. 6800rpm redline, and the power curve is all above 4k.

I don’t sweat the mileage. I drive as inefficiently as I please, and the thing still only uses half the fuel of my old Subaru.

You may have a point, here are the gear ratios:

Manual: Gear Ratios: 1st: 3.308, 2nd: 1.870, 3rd: 1.303, 4th: 0.949, 5th: 0.727
Auto : Gear Ratios: 1st: 2.996, 2nd: 1.679, 3rd: 1.067, 4th: 0.761, 5th: 0.552

It looks like 5th gear on the Manual isn’t much longer than the 4th on Automatic. I still don’t understand how CR got 33 MPG on the manual.

How do you get up a mountain or drive on snow with an automatic?

Why do you care so much about Consumer Reports? The EPA numbers are done on a dyno in a closed enviroment with every variable controlled for. They are “scientific” and thus are reasonably comparable across different cars. CR’s numbers are just anecdotes. Maybe the temperature of the air changed, or the temperature of the road, or any number of other things.

Manuals are prevalent in Europe because most European cars are tiny socialist penalty boxes compared to American vehicles. Most Americans drive 5000+lb trucks or SUVs with 5+ liter V8 engines, European cars usually have engines displacing less than 2 liters. When the car is so small, the relatively heavier automatic transmission increases the overall weight even more. There may not be room in a small car’s engine bay to fit 6 or 7 or 8 speed automatic transmissions, and the torque converter sucks up a larger portion of your power when you only have 95hp instead of 300.

As in America, European cars that come with 5+l V8s are also rarely available with manual transmissions.

Just fine, I guess. The torque converter in an auto transmission car is usually gentler and less jerky when starting from a standstill unless the driver is better trained than the average driver¹. So automatics should have less problems getting out of a ditch or starting on a slippery incline. So an inexperienced driver would probably be better off with an automatic than with a manual.

Personally, I still thoroughly prefer manuals, though. Even if I had an auto I’d probably avoid having to let my clutch slip to get to the really low speeds I need when I’m off-road (my 4x4 doesn’t have low gear). Manuals are significantly cheaper, it’s not a problem for me driving it (since that’s what I’m used to, I prefer the extra control), and even on a fairly new and expensive car like an Audi I get a noticeable downshifting delay before acceleration. With a manual (excepting, of course, VAG’s Tiptronic system and the likes), I can downshift in advance and cruise in the best RPM range for accelerating, waiting for the perfect moment to start my acceleration. You see, up here, we often have pretty short stretches for overtaking…
¹ I’ve seen far too many drivers trying to start on really slippery ice or snow and not understanding that if your tires are slipping, stepping on the accelerator is abso-f*ing-lutely the worst thing you can do!