hypermiling potential: automatic vs manual trans
 

Does anyone have any thoughts on the likely hypermiling potential FE difference between identical cars where one has an automatic transmission and the other has a manual transmission?

I've started looking at a new vehicle and i'm currently looking closely at the 2013 Hyundia 5-door Accent. Both the auto and manual have a 6-speed transmission. I suspect that applying the standard HM techniques to each car that the manual should be able to get better FE, but how much better? 5%, 10%? 20%

You may not get many responses, as this is a beaten to death topic here. For more detailed information, I implore you to use the search function.

Short answer, standard. More control in countless ways.

EfficientCanuck, this is an "it depends" situation - with the main criteria being where you do the bulk of your driving:

If primarily highway, choose the car with the better rating, as the deciding factor for best cruising RPM is gearing. (Unless you're willing to do pulse & glide highway driving with a manual over long distances, which most drivers aren't.)

If not primarily highway, the manual affords far more opportunities to drive efficiently than the automatic, regardless of the respective ratings.

Off the top of my head, I can't think of anyone who's compared auto vs. manual percent differences while ecodriving/hypermiling an otherwise identical car. I'm sure it's been done though.

Something ELSE to remember and consider: most automatic-transmission vehicles are equipped with a numerically lower axle/final drive ratio (fdr) than similar manual-transmission vehicles.

Thus, the IDEAL situation for FE is to mate a manual-transmission with an automatic axle/fdr. Of course, you now have to also compensate for the differences occuring at the odometer and speedometer, but it's doable, especially with today's "pulse" vs. yesterday's "geared" odo/speedo sensors.

In the past I've said that I regard the automatic transmission as an evil, destructive technology...in the same category as nuclear weapons, nerve gas, and torture devices.

The Honda Fit is available with an automatic transmission and a 5-speed transmission. The auto is better on the freeway because its top gear is significantly taller than the manual transmission's.

The manual can be driven much better around town--up to 50% in some cases. The manual does not have a problem with engine-off coasting, while the automatic might. The fact that you have much more direct control of the manual transmission and can keep it in one specific gear at any load you choose also factors in, as does the fact that the torque converter in most autos does not lock up during a lot of in-town driving.

But yeah, it depends on the exact differences in gearing, plus where and how you drive, and how good you are at using hypermiling techniques.

BTW, most hybrids are harder to hypermile because some of the standard techniques are built in, and because hybrids tend to be very optimized for the particular driving conditions that the engineers think they will see. So when you operate outside of those conditions, you can easily "fall off the curve" of best efficiency.

-soD

EfficientCanuck, are you planning on installing a kill switch? That is a sure way to improve mileage on a manual and to destroy an automatic.

Apparently, we were posting simultaneously.

I will worry about hypermiling a hybrid when I achieve comparable results with a normal car, but that is a very interesting point!

I've logged ~100,000 hypermiling miles now, under a variety of conditions in a lot of different cars. In my experience, I can expect to achieve 135% of '08 combined EPA in an AT car, and 175% of '08 combined EPA in a MT car.

135% for AT? Obviously, you haven't driven a 2011 LTZ Cruse with it's 'erratic' 6-speed automatic with its 'tall' 3.87:1 final drive ratio, have you?