Real MPG over time

[CXVille]

....

* If I'm sitting at a red light, for what I expect to be more than 30 seconds (or so), I shut the engine off.
* coast in neutral, when approaching a traffic signal, or getting off highway (on exit ramps )

Depending on how long you are idling, it may not save much, and if you are in stop and go traffic (lots of stops) may shorten your battery life with too many starts. Cars designed with auto systems to do this have specific design considerations to manage the load.

Coasting in neutral is a waste of time and effort. When coasting in gear, the engine shuts off all fuel to the engine. It is true that the vehicle slows down more, but it is using NO fuel. Coasting it is using the idle fuel rate, which is greater than zero. If this overslows, you may have to get gently back on the gas, but the mileage at that point is going to be 60+ to reduce the slowing rate. Coasting in neutral may also be illegal in some states.

 

[CaribouMainiac]

CXville says: "When coasting in gear, the engine shuts off all fuel to the engine."

I kinda doubt that a running engine uses NO fuel.... I call that : Bull Sh*t. ( but you are entitled to your opinion, no matter how weak.... )

..... but.... I didn't mention anything about coasting "in gear".... but, I thank you for the info about coasting in gear.... I'll file that insight where it belongs....

As far as the battery goes.... we will see.... I'd be more worried about the starter getting worn out. (which I will pay more attention to, especially right before the 3 year full warranty runs out, .... and since I don't like to pay for repairs, I'll likely trade it in, for a newer model, in June 2015 )

.... gotta go to work, I'll check back at my usual frequency.... (in a couple of months )

 

[SayNoToPistons]

It's called "closed loop", where injectors are full off.

 

[CXVille]

CXville says: "When coasting in gear, the engine shuts off all fuel to the engine."

I kinda doubt that a running engine uses NO fuel.... I call that : Bull Sh*t. ( but you are entitled to your opinion, no matter how weak.... )

..... but.... I didn't mention anything about coasting "in gear".... but, I thank you for the info about coasting in gear.... I'll file that insight where it belongs....

As far as the battery goes.... we will see.... I'd be more worried about the starter getting worn out. (which I will pay more attention to, especially right before the 3 year full warranty runs out, .... and since I don't like to pay for repairs, I'll likely trade it in, for a newer model, in June 2015 )

.... gotta go to work, I'll check back at my usual frequency.... (in a couple of months )

Caribou - Kinda harsh, isn't it? I'll leave it at that and not stoop to your level of name calling.

As for BS - if that is what you want to call it, I guess Toyota doesn't have a clue about their engines:

According to Paul Williamsen, the product education manager at Toyota,All contemporary Toyota and Lexus vehicles (and every other car built since the 1990s that Ive looked at) can detect the condition when engine revs are higher than idle with a fully closed throttle: Under these conditions, all current to the fuel injectors is stopped, and no fuel is injected.

Or GM doesn't either: Tom Read, GMs powertrain spokesman, agrees: Shifting into neutral in an automatic will cancel fuel cutoff. Thus, it is better to remain in gear and let the drive wheels pull the engine airflow down to where fuel cutoff can be enabled or where fuel flow is minimized.

( http://www.caranddriver.com/feature...ng-to-a-stop-do-not-shift-into-neutral-page-3 )

Here are some other links for you.

http://www.popularmechanics.com/cars/alternative-fuel/news/coasting-in-neutral-fuel-economy

http://www.team-bhp.com/forum/technical-stuff/102829-does-coasting-save-fuel.html

And some of those links also discuss reasons you wouldn't want to coast in neutral as well.

But, hey, you know far more than Engineers and programmers who design and build these things. Sorry to rain on your parade, partner.

 

[joemon1984]

Caribou - Kinda harsh, isn't it? I'll leave it at that and not stoop to your level of name calling.

As for BS - if that is what you want to call it, I guess Toyota doesn't have a clue about their engines:

According to Paul Williamsen, the product education manager at Toyota,All contemporary Toyota and Lexus vehicles (and every other car built since the 1990s that Ive looked at) can detect the condition when engine revs are higher than idle with a fully closed throttle: Under these conditions, all current to the fuel injectors is stopped, and no fuel is injected.

Or GM doesn't either: Tom Read, GMs powertrain spokesman, agrees: Shifting into neutral in an automatic will cancel fuel cutoff. Thus, it is better to remain in gear and let the drive wheels pull the engine airflow down to where fuel cutoff can be enabled or where fuel flow is minimized.

( http://www.caranddriver.com/feature...ng-to-a-stop-do-not-shift-into-neutral-page-3 )

Here are some other links for you.

http://www.popularmechanics.com/cars/alternative-fuel/news/coasting-in-neutral-fuel-economy

http://www.team-bhp.com/forum/technical-stuff/102829-does-coasting-save-fuel.html

And some of those links also discuss reasons you wouldn't want to coast in neutral as well.

But, hey, you know far more than Engineers and programmers who design and build these things. Sorry to rain on your parade, partner.

 

[hp79]

Depending on how long you are idling, it may not save much, and if you are in stop and go traffic (lots of stops) may shorten your battery life with too many starts. Cars designed with auto systems to do this have specific design considerations to manage the load.

Coasting in neutral is a waste of time and effort. When coasting in gear, the engine shuts off all fuel to the engine. It is true that the vehicle slows down more, but it is using NO fuel. Coasting it is using the idle fuel rate, which is greater than zero. If this overslows, you may have to get gently back on the gas, but the mileage at that point is going to be 60+ to reduce the slowing rate. Coasting in neutral may also be illegal in some states.

Idling more than 1 minute it where I would see it as better for saving gas, if I knew I will be idling 5 minutes, then I'd turn engine off. This is very rare. There are reports that even idling 20 second is the tradeoff point, but I don't know about our CX-5, and also I don't want premature wear so I don't do this.

As for coasting in N, it does save gas in right conditions, but you are also right that this might be waste of time and effort depending on how hard this technique is for you. If the environment allows and you are comfortable with these tricks, why not? Coasting in gear will completely cut off fuel, but will also slow you down too much, sometimes this is not favorable. Coasting in gear is good when you are going steep downhill.

I'm no expert in hyper-mile, but I find coasting in N works best when there's no cars around you, going slight down hill so you maintain your speed, or in the city where there's almost no traffic and you can predict the next red signal or you are approaching a stop sign on top of a hill. I think coasting would work much better on a manual since you can just press the clutch or also resume by rev matching a little.

Also, when stopped for more than 30 seconds, I put in N to reduce some load. I can check this using OBD2 adapter.

Bad times to be coasting in N would be when approaching stopped vehicles too fast or a red light and you have to use your brakes even more to stop. If you had coasted in gear, it would have saved gas because the fuel cut-off and also the brakes from engine brake.

On a highway, if you go near 70mph, mpg drops a lot, like 24 mpg. Try to go 60mph and you'll get at least 28 mpg.
I'm amazed by people who constantly get over 30mpg in an AWD model. It might be the gas too, 0% ethanol gas gives 10% more mpg in my Elantra.

 

[GAXIBM]

hp79 - Can you really tell by your OBD2 that at a stop light putting it in N saves gas? I read in the service manual in the transmission theory area that the CX-5 autotransmission releases engine load when stopped for a few seconds when in Drive. As soon as you release the brake it reengages. Is this marketing smoke? I can not tell the difference in N and D when stopped with the brakes engaged, by listening to the engine or watching the tack...

 

[GAXIBM]

I think if you watch the instant mpg readout, you can determine when it is better to put it in N or let it coast in gear in any given hill/situation.

 

[addabox]

Second tank, 27MPG with about 60/40 city highway (and a pretty congested highway at that). The instantaneous MPG readout is very educational.

 

[CXVille]

In almost no conditions will coasting in neutral save gas. This thing is running an electronically controlled throttle, and coasting in gear it shuts off all fuel to the engine, opens the throttle plate wide open to eliminate pumping losses, and uses no fuel. NONE. Not a single ounce of fuel - see the links above. The readouts don't go above 99.9 mpg, so you are not clearly told when it shuts off the injectors. On a long, downhill run, where you could coast in neutral, and not lose (or gain) speed, coasting in neutral might be advantageous. Might be. If you are gaining speed, you might as well have used the very slight engine braking, and burned no fuel. If you are losing speed, you will need to accelerate, which is very inefficient compared to light throttle constant load. So, I really don't understand why you think you can get better mileage coasting in neutral.

 

[Sekmor]

Our CX5 just turned over 2000kms, only a month old. Finally got some nice weather and went for a little road trip.
Road trip all highway 500 kms..Half of that the cruise was set at 72 mph (115kph).The rest was 56-60 mph (90-95kph)in the national park.
Since mpg is figured out diff in the US/Can, plus the L/100, I'll list them all.
Real mileage figured out at the pump.
Canadian 41.6 mpg..........US 34.6 mpg..........6.79L/100km.....can't complain about that.

Also if you are looking at window stickers, you'll notice the government changed their fuel mileage tests. Starting with MY2015,, all numbers are a good 10-12% less mileage, which brings it down to more realistic consumption. So anyone shopping for a new car, consider that when comparing 2014 to 2015's. (this is in canada).

 

[hp79]

GAXIBM, I can see the load being reduced with ODB2 tool when in N instead of D. I'm guessing less load is less fuel used.


CXVille, let's put it this way. Coasting in N can use less fuel for your overall trip. You are correct that when you coast in D, there is zero fuel usage. Everyone already knows that. Really. You realize that coasting in D is same as engine-brake, right? The engine does not freewheel like your bicycle would. You are losing all that momentum energy on engine-brake.

Example: On a steep downhill highway, if your speed can be maintained at 55MPH coasting in D,and your trip ends at the bottom of the hill, that is the only time it will save gas (vs coasting in N) for your overall trip. If there were no traffic and no speed limit no laws no danger, best way to use less gas for your overall trip would be let it coast in N downhill even if it reach 65MPH, then at the end of downhill will come an uphill or flat and you still have momentum to go further. Eventually when you slow down to 45MPH then put it back to D and accel back to 55MPH. In case you used enginebrake downhill, as soon as you reach the end you have to pump gas in to maintain 55MPH. This is where the loss will be, if you coast in D.

Another examplenumbers are not accurate here) World has fallen apart by zombie appocolypse. You have one tank of gas, with auto trans, nobody is on the road. Most efficient way to drive is give a good boost so your engine has good 80% load, until you reach 35 MPH. Then coast in N untill speed drops to 25MPH. Put in D and throttle 80% again up to 35MPH, and repeat. Unrealistic, but it gets much better gas mileage.

I used obd2 tool couple times on a 3 miles 30-45 MPH zone in city. When I feathered accel pedal & smooth start & predictive driving, I get about 24mpg. When I used quick accel & coast in N & predictive driving, I get 29mpg. This can help in city driving when there's no cars behind.

My only concern is how much extra wear, if any, would happen when shifting from N to D while moving. That I don't know.

 

[CXVille]

GAXIBM, I can see the load being reduced with ODB2 tool when in N instead of D. I'm guessing less load is less fuel used.


CXVille, let's put it this way. Coasting in N can use less fuel for your overall trip. You are correct that when you coast in D, there is zero fuel usage. Everyone already knows that. Really. You realize that coasting in D is same as engine-brake, right? The engine does not freewheel like your bicycle would. You are losing all that momentum energy on engine-brake.

Ten or twenty years ago this was correct. Now, with drive by wire technology and the SkyActive technology, this comparison is not correct. They do a variety of things to significantly reduce pumping losses (engine braking). I do not have the luxury of knowing all that Mazda does, but I am willing to bet that it includes: Declutching the transmission somewhat to reduce braking losses, opening the throttle to reduce pumping losses, and we know they shut off all fuel to the engine.

I agree that under specific circumstances, coasting in neutral will increase mileage. But this is where the slope of the hill is very shallow and would require significant throttle input to maintain speed, which would be greater than the idle fuel consumption you would see running in neutral. But, without a separate OBDII readout, and knowledge of specific fuel consumption during specific conditions, knowing when this will occur is going to be difficult.

My point here is simply to prevent folks from wandering through, looking for methods to increase fuel mileage and thinking coasting in neutral, which is illegal in many places is some kind of a panacea. It is not. For most folks, it won't help at all, because it will be way mis-applied. For you, with the separate OBDII readout, and an understanding of the systems, it may be advantageous.

Oh, and not everyone understands that the fuel flow is completely shut off during coasting in gear - read CaribouManiac's tirade calling BS on that.

 

[brandini]

I don't think Mazda opens the throttle plate when in overrun (the condition of coasting in gear) at least I have not seen at said anywhere from Mazda.

The iffy part is the shifting between N and D while moving, it's going to be a LOT more wear on the torque convertor clutch and I don't think that's going to pay out in the long run.

 

[Beefy]

I don't think Mazda opens the throttle plate when in overrun (the condition of coasting in gear) at least I have not seen at said anywhere from Mazda.

The iffy part is the shifting between N and D while moving, it's going to be a LOT more wear on the torque convertor clutch and I don't think that's going to pay out in the long run.

Not to mention the added delay if you have to suddenly apply power for safety reasons. Coasting in neutral is stupid and unnecessary.

 

[brandini]

High five.

 

[jpaulatkinson]

My CX-5 AWD GT is only 210 miles into its break-in: 17.9 mpg (40% highway / 60% city). Gulp.

 

[brandini]

That'll happen with old gas and short trips in a hilly land. Manual mode and engine braking will help you use the breaks less during descent and also uses no gas on overrun.

 

[Bon Scott]

My CX-5 AWD GT is only 210 miles into its break-in: 17.9 mpg (40% highway / 60% city). Gulp.

I was getting similar (12L / 100 kms....19.6 mpg) when I first took delivery of my GT back in February. I was not impressed at all considering what I was being told by people (including sales reps) and what I was expecting. When I complained, I was told that you get worse mileage in cold weather...and that the mileage would increase as you break the vehicle in. I'm now averaging 10.2L / 100 kms....23.06 mpg). I'm trying to coast as much as possible, I don't go hard on the gas from a dead stop, and I use my cruise control as much as possible (even in the city). It's still not what I was expecting (no where near it, to be honest)....but I'll take even a small improvement. I still love the vehicle.

Bon

 

[brandini]

To properly break in an engine you NEED to drive it hard after the fluids have warmed up for the rings will never fully seat.

Find a twisty road and don't upshift as often as usual, engine brake, and then take it easy for a while to let it come down to normal temperatures. Cold starts on this motor really suck a ton of gas so a block heater will help greatly in winter.

Also accelerating with a bit of oomph lets the engine get into cruise sooner so give it a *little* more than usual then hit cruise like you have been and you should see better results.