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Old 02-18-2007, 12:50 PM   #41
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I will give the Metric thing a try today. I'll also see if you can switch back and forth without having to convert back to gallons.
I just tried it and saw "0.3 LPH". Soooooo, I think there is no round-up. Since it is not "0.1 LPH", I think that the units are English-centric, which would make sense for a product developed in the USA.

I don't think changing units will make any difference in MPG, .

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Old 02-18-2007, 01:31 PM   #42
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Same here

I had the same thing.
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Old 02-18-2007, 03:37 PM   #43
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yeah but that is .75gph maybe you can't burn at any lower a rate - guess I need to try it in my xB and see if it gets lower than the .2 - 1. gph I see all the time when warmed up...
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Old 02-19-2007, 10:34 AM   #44
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Now if I just had hills big enough to do this on, our hills are very gradual around here. Enough to suck up gas going up, but barely enough to glide down and see much of a difference........... I have ONE hill that I can drift down .7 of a mile IF no one is behind me because at the end I am at a crawl - again, very gradual. That being said, I do live in the highest point of Florida - yep, the Florida mountains.
Get a little speed up before the downhill. Makes the hill last a little longer and keeps you from getting run over. If you coast for .7 mile, your MPG should be 10% better for the following 7 miles. Add 'em up and they amount to something. Pulse and Glide can be done on level ground. 60 to 40 works pretty well for me but only if I glide in neutral, engine off.

Get in that Toyota and come see us in Colorado. We'll go trout fishing.
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Old 02-19-2007, 12:44 PM   #45
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Ahhh, but here's the catch. I do just that BUT the road has a HUGE bump at the bottom PLUS it turns to a rocky dirt road PLUS it switchs to 15mph in the area where I'm capable of still coasting 30mph PLUS the ONE house on the road in the 15mph area has a cop as a best buddy, he's always there in that 15mph zone. He even waits for me sometimes at 0500am - pretty cool guy as I am normally cruising 35-40mph through there at that time of the morning, This is really out in the middle of nowhere with no side roads, kids etc.

I do have an alternate route I do an engine off coast on when I am driving my Metro, HUGE savings and it is about .5 of a mile. Always cars on that road though, I hate traffic.

Toyota still needs work, I need to find the time (and motivation and $$$) to work on it. BTW, if you're still in Daytona and drove out PM me, I'm just a few minutes off I-10 - I'll let you take the Insight out for a spin.

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Get a little speed up before the downhill. Makes the hill last a little longer and keeps you from getting run over. If you coast for .7 mile, your MPG should be 10% better for the following 7 miles. Add 'em up and they amount to something. Pulse and Glide can be done on level ground. 60 to 40 works pretty well for me but only if I glide in neutral, engine off.

Get in that Toyota and come see us in Colorado. We'll go trout fishing.
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Old 02-19-2007, 01:36 PM   #46
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My hunch is that a diesel would, but an electric wouldn't. The losses for an electric drive tend to increase with load(P=(I^2)*R)

Not sure about all diesel?s, but my TDI uses no fuel coasting in gear down hill. At idle scangauge will show about .2L/hr once warm. If I am going down a hill in 5th with no throttle added it shows 0.0L/hr, if I push the clutch in it goes back up to .2L/hr.

So the big debate on the TDI forums is whether to coast in neutral or coasting in gear. Of course you slow down a lot sooner coasting in gear.

If I have to stop I have figured out how far out I can coast clutch in to make it just right, or if I am in traffic how far out I can coast clutch out, no throttle. From the testing I have done it is better to coast in neutral at .2L/hr then coasting in gear at .0L/hr because you have to stay of the throttle longer leading up to a coast in gear (assuming a flat run out).

Unless you have just the right hill to gain no speed in gear and have to slow down anyway, I use neutral.
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Old 02-19-2007, 01:58 PM   #47
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Not sure about all diesel’s, but my TDI uses no fuel coasting in gear down hill. At idle scangauge will show about .2L/hr once warm. If I am going down a hill in 5th with no throttle added it shows 0.0L/hr, if I push the clutch in it goes back up to .2L/hr.

So the big debate on the TDI forums is whether to coast in neutral or coasting in gear. Of course you slow down a lot sooner coasting in gear.
Just compare it on a KE+PE/top to KE+PE/bottom basis (I'm guessing it depends on the hill). You can calculate the difference in energy between the car's initial state, higher up on the hill, and it's final state, lower down on the hill. Compare these initial states to find out which car, in gear/no fuel or out of gear/little fuel, gains more energy from rolling down the hill. Since the car out of gear is idling, calculate the energy used while idling multiplied by the appropriate modifier for diesel engine/transmission efficiency, and account for it including it in the car that's out of gear's delta E. You could test this on a few different hills to get a curve of best fit, and approximate the grade where it becomes better to keep it in gear, or coast in N, barring of course speed limits.
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Old 02-20-2007, 03:20 AM   #48
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Your test results agree with my driving style. I coast the downhills with the engine off and only use engine braking on steep downgrades where my speed would rapidly get too high or where there is no straight runout area at the bottom.

An extension of these tests would be to test the uphills. Do you get better FE if you accelerate on the flat at the bottom of the hill to build your speed up before reaching the bottom of the hill so you can get further up the hill before having to drop into a lower gear, or is it better to maintain the lower aero drag of your normal cruising speed and accept having to drop into a higher fuel consuming lower gear earlier on the uphill?
Sorry, I first thought your reply was directed to someone else.

I have done no official tests on uphills but have been driving in the manner you describe by accelerating before and quite often during uphill climbs. I almost always do this on hills not too long, i.e., that I can see the crest. I am sure I have improved my uphill FE with these methods.

Longer climbs I get questionable payback for increased approaching speed. But during long climbs I will accelerate if my instant MPG drops below 30 MPG. When my SG II drops into the 20-30 MPG range, extra throttle does not lower the MPG reading substantially(when it's that low, how much lower can it get?). Quite often I can level off after acceleration to a higher speed and see much improved MPG readings for a time. I downshift only when absolutely necessary and when I do I will accelerate immediately to gain enough momentum to get back in 5th gear as soon as possible.

If you drive this way, I would like to hear your assessments.
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Old 02-20-2007, 04:30 AM   #49
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... I downshift only when absolutely necessary and when I do I will accelerate immediately to gain enough momentum to get back in 5th gear as soon as possible...
Do you drop to the next lowest gear, or an even lower gear so you can accellerate better?
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Old 02-20-2007, 07:11 AM   #50
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Do you drop to the next lowest gear, or an even lower gear so you can accellerate better?
I always drop into the next lowest gear. I don't very often go lower than 4th. In the past, if I let my car pull way down 5th, it was also too slow for 4th to pull strong. Then I would use 3rd to bring it back up. I do not skip shifts often.

Keep in mind that I have a 130 HP 2.0 liter engine. But it may not be as different as it seems. At my 10,000 ft. altitude, I may be losing 35% of HP and torque. Actual barometer readings here are in the 21-23 in. Hg area, vs 29-31 in. Hg at altitudes of 0-2000 ft. What this means is that I have about one third less atmospheric pressure pushing air into the engine. Like a supercharger in reverse.
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