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The Drive Thru Not Taken....

Discussion in 'Fred's House of Pancakes' started by The Electric Me, May 27, 2010.

  1. The Electric Me

    The Electric Me Go Speed Go!

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    Okay, so as some of you might know, and I'm sure most of you don't care...I recently bought a new car..but it turned out to be a Honda Fit. It's averaging about 30mpg and so far I love it.

    But I just thought I'd share something with Prius Chat. The Fit has a very simple instantaneous and average per tank MPG monitor, which I use, it's not anything as detailed as The Prius hybrid display, but it does help encourage economical driving and does give you and idea of how you are driving.

    Anyway, last night, I fill up, reset trip odometer and set the display to the average MPG per tank monitor...which is what I keep it set on most of the time. Then I go to the nearby fast food joint drive thru. There is a line and I'm (gasp) idling while waiting in line. So as I'm waiting I'm watching my MPG meter. I can visually watch the MPG average drop....10, 9, 8....

    Well not really a big deal. Every automobile I've owned was doing the same thing while sitting idling...the difference being I did not have a monitor showing me how I was wasting gas. But as I watched the numbers drop...I have to admit it occured to me how nice it would be to have a vehicle that would shut off automatically in a situation like that......kind of like a Prius or a Hybrid...

    Thanks to Prius Chat and the hybrid information I've gained over the past year or so, I guess I'll be turning my engine off as much as I can. Either that or I walk in and get it to go.
     
  2. daniel

    daniel Cat Lovers Against the Bomb

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    Please note that starting a conventional car engine puts a LOT of wear and tear on the engine. Your tank average was dropping so fast because you were at the very start of your tank. You were probably burning about a thimbleful of gas an hour while idling. You'll save very little gas, and wear out your engine faster, by turning it off at every pause in traffic or fast-food line.

    The Prius engine has unique design features to allow frequent starts and stops: It uses variable valve timing and its powerful battery and MG1 to spin the engine up to 1,000 rpm before giving it gas and compression. Your Fit does not have that, and as much as I'd like to see everyone use less gas, I think it is ill-advised to be turning your engine off all the time.

    (Better to leave the engine off entirely, and drive a Leaf. :D )
     
  3. The Electric Me

    The Electric Me Go Speed Go!

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    Thanks Daniel, and I know. I agree that this was just a passing thought as I happened to be sitting in drive-thru and based more on the fact that I've never owned a automobile with an instantaneous MPG meter before, and not really a reality that I think is all so horrific. The Fit isn't a Hybrid, but for a conventional ICE it's definently on the efficient side of the ledger.

    I have gotten and found different advice concerning turning off your engine. To me, I agree that wear and tear on starting components would be a risk and in most regular driving situations I also think it's dangerous. But some people do recommend turning off your engine as much as possible. For me? I'll probably just do what I have always done, which is, if I'm in a Drive Thru and it seems everything has ground to a halt and I'm likely to be sitting for 3 minutes or more, I'll turn off the engine...I did this with the 93 Accord and every vehicle I've owned. I also turn off my engine like most people, in a traffic jam/accident situation when traffic is completely halted.

    Otherwise, as annoying as it is to be forced to be burning fossil fuel while sitting relatively still....I guess I'm forced to do it. But the times are a changing....Prius, soon the Plug In Prius, Volt, Leaf...

    Here's hoping in the future Drive Thru's become quiet and smogless places.---hey it's a first step.
     
  4. San_Carlos_Jeff

    San_Carlos_Jeff Active Member

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    That's "old school" thinking. With the advent of fuel injection, better oils, tighter tolerances, etc this is no longer the case. There are lots of places on the web that talk about this, here's one example:
    Idling Your Car
     
  5. drees

    drees Senior Member

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    Exactly. If you know you're going to idle for a bit and don't need to restart in a hurry, turn the car off. Auto stop-start should be included on all cars so it's automatic in situations like drive-throughs.
     
  6. daniel

    daniel Cat Lovers Against the Bomb

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    A quote from the above linked page:

    This is patently absurd: My Prius burns less than a gallon of gasoline if I drive it for an hour at 50 mph!!! Of course, the Prius is a more efficient car than most, and it does not idle for an hour. But I once left my Civic running for several hours to recharge the 12-v. battery after carelessly allowing it to run down, and my fuel gauge did not even show the difference.

    The article speaks about wear and tear on the starter; but I was thinking of wear on the engine itself when it is turned over without oil pressure and gasoline is sprayed into the cylinders before the engine is turning fast enough to ignite.

    In other words, they are claiming that idling uses as much fuel per minute as driving 30 mph.

    Note that in the earlier quote they were claiming that idling uses more gasoline then driving a Prius 50 mph.
    They can't even make up their mind whether to recommend 10 seconds or 30.

    I would agree that excessive idling is not good. But shutting off the engine at stop lights or at reasonably fast-moving drive-throughs seems excessive.

    (Note: I never use drive-throughs. I always go inside. I also don't permit the consumption of food in my car.)
     
  7. bisco

    bisco cookie crumbler

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    i believe a 12 cylinder chrysler engine burns a gallon an hour when it's off.;)
     
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  8. San_Carlos_Jeff

    San_Carlos_Jeff Active Member

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    Fuel management is so good on newer cars there is no extra unburned gas going into the cylinders at start up, or any other time. There is some more engine wear at cold starts, but what the OP is talking about isn't a cold start it's a warm start. The added wear is close to insignificant. IMO they picked 30 seconds because it's a realistic number, stopping and restarting every 10 seconds would get old pretty quickly.

    I went through a drive-thru today for lunch, it was nice to have the Prius off for most of it :)
     
  9. daniel

    daniel Cat Lovers Against the Bomb

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    I do like the quiet of the Prius at stops. I like that it stops its engine. But I like the Xebra better because it doesn't even have an engine.
     
  10. drees

    drees Senior Member

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    Depends greatly on the vehicle. My Subaru 2.0l burns about 0.3 gallons/hour idling. The Prius burns about 0.5-0.6 gph during warmup.

    Pretty easy to see how a gas V6 or V8 could easily burn 1 gph idling.

    I'm sure that someone here with a Scangauge has measured other cars.
     
  11. daniel

    daniel Cat Lovers Against the Bomb

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    Which lasts for two or three minutes!
     
  12. fuzzy1

    fuzzy1 Senior Member

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    My 2.5L Subaru starts at about 0.85 gph cold, gradually dropping to the same 0.3 gph as yours when warm.

    My Prius seems to have nearly the same figures. While theoretically it should be able to idle at about 1/4 the fuel flow of my Subaru when warm, the Stop-Start shuts it completely off long before it gets there.
     
  13. The Electric Me

    The Electric Me Go Speed Go!

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    This is exactly what I meant when I said I've heard and gotten conflicting advice about turning off your engine.
    I love efficiency. It's what brought me to Prius Chat, makes me admire The Prius. But I also admit I'm a bit of an old school thinker.
    While I can get onboard with the obvious reality that keeping your engine not running as much as possible, saves fuel. Also I can agree that in most modern ICE's with EFI engines they are much more efficient at start up, thus potential damage would probably be less than an "old school" thinker would think. However, even before this thread I read the before linked article about turning off your engine while idling. I just can't get onboard with the advice as presented.

    Turning off your engine if you are going to be idling for 10 seconds or more? First of all I think there is a distinction between "driving" and potential stop and go...and situations where you are idling your engine and can determine more or less exactly how long you might be idling your engine.

    Owning a hybrid, which obviously has an entire system inplace to automatically utilize electric motors, computers, and integration of electric power to offer the shut off of your ICE while maintaining the instantaneous ability to hit an accelerator pedal and create momentum....is simply a totally different animal than owning a coventional ICE automobile.

    I try to be honest with myself and others on both sides of the ledger. While I have regrets to the extent that with an ICE I simply do NOT have the efficiency advantages of a Hybrid.

    I have, and do employ a degree of hypermiling techniques. Admittedly not extreme at all, but the simple embracing of a few techniques and general awareness of the philosophy and I have witnessed...(especially with my previous older car) how much more efficient you can force any vehicle to be.

    However, you have to accept the reality of what you have. Bottom line for me, with most suburban, city driving, I think turning off your ICE engine using the parameter of if you are idling 10 seconds or longer....is just too dangerous, even if it's not particularly damaging to the engine, even if it does offer some fuel savings.

    I just have to be honest with myself and say if that was a SUPER priority to me, I should of bought a Prius.

    I think trying to force an ICE automobile into behaving as something it is NOT, and ultimately wasn't designed to be used in that manner is dangerous.

    Also without the automatic nature of shut-off as it exists in a Hybrid? With most of my stop and go suburban driving the simple act of trying to determine how long I might be idling would be quite daunting. If 10 seconds or longer is the rule, IMO I'd be turning my engine off and on way more than I'd feel comfortable doing.

    Also in a conventional ICE in operational traffic, idling or not, I think it is often just too dangerous to be sitting with your engine off. Even if we are talking only "seconds" or less to re-ignite an engine....often if an emergency situation arises you don't have those seconds.

    No, investigation of Hybrids, has led me to a greater admiration for efficiency. I think the future will be what we consider today "alternative" types of transportation. I champion The Prius, Electric and Hybrid drivers. I try to be as efficient as possible with the choice I have currently made. But I think taking a machine out of the parameters inwhich it was designed to operate...and IMO coventional ICE automobiles as they are offered today aren't designed to be shut on and off constantly while being "driven" in the real world.

    I'll say it in a Honda Fit Forum, Ill say it in Prius Chat. If you want an engine that turns off when stopped.....buy a Prius. Otherwise face the reality of the machine you have at your disposal.
     
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