Coast in-neutral vs in-gear: I've been challenged to show the numbers

[wdb]

Originally Posted by Old Mechanic

Coasting in gear is not really coasting, since there is engine braking involved unless clutch disengaged in a manual).

Is that still as true as it used to be, this far along the trajectory of Moore's Law? My wife's 2011 CRV (they only sell them as automatics) rolls out pretty far in gear, when I'm moving at speed on a flat road; it doesn't quite feel like it's in neutral, but there is minimal engine braking taking place. When going downhilll however, I can really feel the engine braking the vehicle. I attribute the difference to Honda's transmission management logic.

[reb01501]

Originally Posted by wdb

Is that still as true as it used to be, this far along the trajectory of Moore's Law? My wife's 2011 CRV (they only sell them as automatics) rolls out pretty far in gear, when I'm moving at speed on a flat road; it doesn't quite feel like it's in neutral, but there is minimal engine braking taking place. When going downhilll however, I can really feel the engine braking the vehicle. I attribute the difference to Honda's transmission management logic.

I don't understand the point you're trying to make. You start by questioning whether engine braking is occurring (and why is Moore's law relevant?), and then go on to describe you actually do observe it occurring. Seems to me you've answered your own question.

[roosterk0031]

Automatics tranny engine braking depends on the car. Neither of my GM auto coast hardly any different OD or N. If engine braking is wanted need to put them in D or 2. Stratus engine brakes and downshift and brakes even more, so it needs to be shifted to N to coast well.

I wonder if the CRV is it keeping it's torque convertor locked going down hill to avoid speeding up. But unlocks it when coasting as long as not gaining speed.

The stratus if cruise is set and go down a hill large enough for it to pickup speed, will disconnect the tranny, the engine revs to 3,000 rpm, waiting for the car to get back down to the set point where the tranny will reengage, on hills that I know it will do it I will cancel cruise, shift to N, and then reengage tranny & cruise once the coast if over.

[UltArc]

Originally Posted by jsatter

You have to be on the gas longer to reach a coast point too. You lose on both ends when you coast in gear.

I disagree with this. But only at certain speeds. When I go to the cemetary near me, I park on top of a hill. The scAngauge resets, and I roll forward and bump start into first, go to second and third, going back up the hill on the other side, she needs second, but by time I am out I get to almost 30 mph, 33-35 mpg, and use zero throttle pedal. Now I don't kow how much fuel I use, but it must be minimal, I put it into gear at 4xx rpm range and she wants to climb back up.

So for me, in THIS case, in gear coasting is very beneficial. Or maybe it's not technically coasting since I start at a stop. If this is the highway we are talking, then hands down, I totally agree. But unless I am 30+ mph, going uphill, or can see my stop point, I (think) I am better off in gear.

But those are strict standards. So I can happily agree usually out of gear coasting is more efficient than in gear.

[ecomodded]

Coast down a secluded hill from a set starting point, till you reach a stop,mark the spot. Repeat it in neutral , repeat it all again. Then crunch the numbers.

[Fat Charlie]

UltArc- Sorry, I wasn't trying to get in your face too much. But I was really hoping that you were joking in your hope that ksa8907 was joking.

To the challenge of "Find me some numbers," The only real answer here is "I can't." It can't realistically be tested for. The sheer obvoiusness of riding the brakes being bad for FE really turns the question around: Don't ask me to explain the benefits of coasting in neutral, explain to me why you think staying in gear is better than popping it into neutral.

[RiceCake]

Originally Posted by ecomodded

Coast down a secluded hill from a set starting point, till you reach a stop,mark the spot. Repeat it in neutral , repeat it all again. Then crunch the numbers.

In neutral is essentially guaranteed to coast further but proves nothing. The real test would be to see if the extra fuel needed to idle the engine while in neutral is /less/ then the fuel saved by driving the engine with the transmission in gear.

[user removed]

Coast in neutral, at 70 MPH, down a 5% grade on the Interstate (in neutral which is the DEFINITION of coasting) with a tractor trailer on yer butt, then shove it in gear and see what happens.

regards
Mech

[UltArc]

Originally Posted by ecomodded

Coast down a secluded hill from a set starting point, till you reach a stop,mark the spot. Repeat it in neutral , repeat it all again. Then crunch the numbers.

I hope I remember to test this next week! I am rather curious about this now. At first, for MY situation, I thought it almost for sure, but really breaking it down, I don't know. I normally bump start my engine, next time I won't, so it stays fair. I think in neutral there will be a lot more variables in play. In gear it is smoother, but hopefully we'll see soon.

Originally Posted by Fat Charlie

UltArc- Sorry, I wasn't trying to get in your face too much. But I was really hoping that you were joking in your hope that ksa8907 was joking.

To the challenge of "Find me some numbers," The only real answer here is "I can't." It can't realistically be tested for. The sheer obvoiusness of riding the brakes being bad for FE really turns the question around: Don't ask me to explain the benefits of coasting in neutral, explain to me why you think staying in gear is better than popping it into neutral.

Honestly, I did take it as hostile, but being it all in text, and this being a friendly forum, I figured I just took it the wrong way. And maybe my comment seemed hostile, too, so I try not to take any offense from anything. No harm, no foul.

I see your point in that, but some people are not very open minded :/ They get an idea, and that is just so until proven otherwise. My family is very much stubborn in this way. For years I have been telling them to unplug chargers and tvs and whatever they don't use, as it drains power. They finally did it to shut me up, and now they must constantly unplug everything that is not theirs, because of the energy they save.

Even on here, I remember someone switched to a funnel air intake rather than stock on a Focus I believe, and did not do very scientific reporting. The response was not very friendly lol. I know now to watch my exhuast when I talk about FE numbers lol.

[reb01501]

Originally Posted by RiceCake

In neutral is essentially guaranteed to coast further but proves nothing. The real test would be to see if the extra fuel needed to idle the engine while in neutral is /less/ then the fuel saved by driving the engine with the transmission in gear.

That's why I wanted a net usage measure, not a measure of usage during the coast.