I didn't see any threads with a good compilation or discussion of AT MPG reduction techniques. The few I could find devolved into rants and flames quickly.

Anyone have any experience with these mild techniques?

- DFCO (P&G while in gear) at highway speeds
- DFCO in town (just coasting between stops)
- Putting in neutral while stopped
- Putting in neutral while moving (P&G w/o DFCO)
- Turning engine off while stopped (some discussion on FitFreak)
- Turning engine off while moving (lots of discussion on FitFreak)

I've just started using some of these although I'm avoiding turning the engine off while moving and putting in neutral in moving. Which one's have a potential for damaging the AT? Anyone try fast accel vs slow accel during highway or in town traffic?

I will probably get a scan gauge at some point to help judge this better. As near as I can tell the scangauge guesses at instant mpg since it can't read real fuel consumption. Instant mpg is calculated from estimated airflow (MAP) and assumes the ECU maintains 14.7 air/fuel ratio.

Any more radical techniques just for the AT others have found effective?

Thx RG

 

I'll put in my input as an AT owner who recently got a ScanGauge. I can easily observe what affects economy.

P&G is not very practical - IMHO, it's best to pick a MODERATE speed and set your cruise control.

DFCO in 'city' driving - I've been using S mode with paddles in City driving (I mean downtown Austin, I have to drive through downtown to get to my office) and have observed a couple things: It's difficult to get DFCO to engage, partly due to the fact that 2nd gear is just not efficient to cruise in, even if the revs are low. Partly due to the fact that you usually don't have a long distance to coast. I've found it's better to shift to 3rd if you're close to 30mph, and can go at least a couple blocks. If it's safe, downshift to 2nd with no throttle input and get a little DFCO.

Neutral while stopped - I've observed my fuel consumption gauge, and noticed that sometimes idle in D can have as low consumption as idle in N. I'm not sure why, but maybe it has to do with what gear the transmission was in before it engaged it's clutches, or if it's temperature related. With the ScanGauge, I see usually 0.19-0.22GPH in N (or P). In D, it can go up above 0.30, but I have seen it drop to 0.22. So, I think it's best to see how much fuel you're using at the time, combined with the length of the light you're at before shifting to neutral.

Neutral while moving - Not likely a good idea... the engine will be idling, however depending on the distance you can coast, you might get GOOD fuel efficiency for that distance. If you're coasting to a stop, it's just a better idea to leave it in gear which will result in DFCO, and increased deceleration.

Turning off the engine while stopped - Sure, it doesn't take much running to offset the engine being off. I've heard 7-10 seconds of idle burns the same amount of fuel as starting. However, starting consumes power from the battery, which has to be recharged - increasing the demand on the alternator, and thus increasing it's drag on the engine. And it puts more use on the starter motor and solenoid. Unless you're going to be stopped for a considerable amount of time, it's probably not a good idea to shut off the engine.

Shutting off while moving - Same drawbacks as above, but also leaves you less able to maneuver if needed.


As far as the ScanGauge's readings, I'm not sure if it calculates based on MAP readings and stoichiometric air/fuel mix, or if it's using average injector duty cycle factoring engine size. I DO know that the ScanGauge will use your fillup data to calibrate itself, so it will get more accurate the longer you use it. Some data users have posted show less than 2% variation, so that's not bad. I'd consider it pretty accurate. I highly recommend getting one.

 

Good stuff Fray. I take it you feel paddle shifters in city and automatic on freeway is the most efficient? Any paddle shifter tips you'd give us from what you've found using ScanGuage?

 

You're right, I'm using Sport mode with the paddles in city driving, and shifting to Drive when I get on the highway.

I try to shift before 3krpm, and when permitted (a few blocks before having to stop), shift to a higher gear. Keep throttle input to the minimum needed to accelerate. A feather soft touch on the pedal is preferrable.

2nd gear is NOT efficient to cruise in! If you're trying to hold speed, even if it's kinda slow for 3rd, it's more efficient to cruise in the higher gear.

Sometimes I'll downshift to 2nd when slowing, which can engage DFCO, but often times there's just not enough distance to get much out of it.


City driving is always going to result in low economy, sadly.

 

Thanks Fray and Wuze. As you've indicated, maintaining constant speed, putting in neutral at stops and DFCO seem reasonable and safe ways to increase mpg with the AT without adding wear & tear. I don't have the paddle shifters so I have little opportunity to control shifting during city driving other than feathering the gas pedal. Since the pedal no longer directly controls the throttle, maybe it should be the DBW pedal.

Any others want to post their experiences and observations?

 

Another question: Although all the drivers on here constantly post saying we shouldn't be shifting mid-turn and stuff, but this is only realistic when the light's green. Since I started reading up this eco section, I've been doing nearly all city driving with the paddle shifters, which is not only more fun, but seems to be more economical when done correctly. My problem is going from a stop and turning, upon acceleration, I can't keep up with the paddle shifters rotating with the wheel and the wheel blocking my speedometer (although I can play by ear and know when I'm about 3K RPM, I play music pretty loud in my car ), leading shifts into 2nd gear being closer to 4K RPM than 3K RPM (which seems to be the ideal point to shift). Is this a huge issue and should try harder to shift at 3K?

I also never drive in 5th gear in the city, even though I get to 3K RPM in 4th. I shouldn't shift up, should I?

Thanks guys. :b

 

Have you tried starting in 2nd? Often you don't need great acceleration to keep up with traffic, especially with today's gas prices it seems that all the SUV's are going slower than the small cars!
Just wondering if starting in 2nd helps the mpg?

 

Anyone able to answer my questions as well as kndlewis's?

 

any of you have a scangauge? it'll answer all your questions. great tool for those who want to get good fuel economy

 

Fray does...

... Which is why I'm waiting for his input as he knows his goodies.

 

From hypermiling my 08 Escape I've picked up a few things, since it is AT and 4wd that eliminates gliding and picking where I want it to shift.

The best gains for an AT I've found are:
DWB (Drive With Buffers, Driving Without Brakes): You Drive as if you have no brakes, and get off the gas much sooner than you otherwise would.
DWL (Driving with load): let speed bleed off going uphills, pick it up going down.

Learn your shift points. The more time you can spend in 5th the better. Find out the minimum speed the car will shift into 5th with light throttle and try to keep it around there. Holding a lower gear costs you 4-5 MPG. So unless the car absolutely can't accelerate in top gear, keep it there.

The brake pedal is the fail pedal. If you find yourself going for the brake, try to plan ahead better, both by keeping your distance from traffic and knowing your route and terrain.

The less time you spend on either pedal, the better. And I will second solbrothers scanguage recommendation. When you see which things you do that cost you fuel economy, you tend to stop doing them real fast.
In my 17/22 MPG rated 08 Escape I have been pulling 26-27 MPG tanks for 3 months now.

 

OK, I got the point of the ScanGauge. I just got one myself so I'll see about starting in second. All the other suggestions posted have helped my get my first 40 mpg tank with my AT! Hopefully the ScanGauge will help my get all my tanks at 40+.

 

So I take it if you're neutral coasting down a hill and have to hit the brake a lot it's using just as much fuel as just keeping it in drive? :X I neutral coast down all hills now but those large inclines where I'll get to 50+MPH I need to brake.

 

why would you need to brake? is there something in your way? if not, BE A MAN!!! DON"T BRAKE!!!!

 

lol @ solbrothers.

If the hill is so steep that you are picking up too much speed, just leave it in D.
-or-
Accelerate slowly enough to the top of the hill, so that you are going the correct speed at the bottom, with respect to traffic flow.

 

Going down the hill with the car in gear will use zero gas. Going down the hill in neutral will burn fuel to keep the engine at idle while in neutral.

Those with scan gauges noted the ECU shuts off the injectors (zero fuel consumption) if you take your foot off the gas and the RPM is above 1000. Putting the car in neutral keeps using fuel to maintain idle speed. If you can tolerate the slight increase in drag, keeping the car in gear with your foot off the gas pedal.

 

Haha oh crap this is the most useful post I've seen in this forum section, thanks.