Minimum Speed Limit?

Discussion in 'Fuel Economy' started by m6soto, Mar 30, 2008.

?

What speed do you dare do on a 65mph freeway w/ traffic scooting along at 70mph?

  1. 40-45mph

    3 vote(s)
    3.4%
  2. 45.1-50mph

    7 vote(s)
    8.0%
  3. 50.1-55mph

    24 vote(s)
    27.3%
  4. 55.1-60mph

    36 vote(s)
    40.9%
  5. 60.1-65mph

    18 vote(s)
    20.5%
  1. bestmapman

    bestmapman Fighting untruth and misinformation

    WOW, I am glad it worked out for you. My experience is it is better to not to argue with the police. The bottom line is that they can stop for almost any reason and check you out.
     
  2. Chuck

    Chuck just the messenger

    justpassinthru,

    I agree there are pullovers that are questionable and experienced 1-2 myself, although they were in my lead-food days. I've driven as you have described, but so far nothing has happened...other members really have not had a problem either. All I can recommend for anyone that thinks an officer is about to do a pull over in such a situation is to gradually speed up to maybe 50mph.

    You might want to consider coming back and not be a stranger. The experience at CleanMPG is while your exprience is unpleasant, it's rare.
     
  3. Nikki

    Nikki Well-Known Member


    Justpassinthru, my father was a police officer in the 1960s & 70s. A big thing I learned from dear old dad, was cooperate when pulled over or approached by a police officer. Don't challenge or argue. Those men & women are just trying to do their job which is to keep us all safe. These days it's really hard to tell the good guys from the bad guys so their life is on the line every shift.

    The last time I was pulled over I was doing 47 in a 30 mph zone. It was late at night with no other cars around. I was extremely polite and ended up with a warning rather than a big ticket. Here there is a huge jump in the fine if you are 15 mph or more over the limit.

    Bottom line ... When pulled over, move off the right of way if possible. Put your hands on top of the steering wheel and tell the officer what you are going to do before you do it. Be respectful & don't argue. That will take you a long way.
     
  4. WD-40

    WD-40 Member

    I believe the minimum speed on the highways here in Canada is 60 KPH 40 MPH ..
    Of course there are those that believe its actually 60 KPH over the posted speed ..
     
  5. nerys

    nerys Banned

    Well the tailgaters comes down to EGO's IE its not about wanting to tailgate you so much as getting submission. They want YOU to change not THEM to change. Silly crap is all it is. I just gradually slow down as slow as it takes for them to get the hint. I never "hit" the brakes thats a safety issue. I also never go too far below the speed limit (unless I am alone on the road) this is a safety issue NO amount of mpg is worth compromising ANY level of safety. Period.

    Minimum speeds only apply to a speeding TICKET. If an officer determines you are a safety hazard it does not matter if your going 30 45 or 60mph. IE you an not defeat a safety ticket with a claim of I was above the 45mph minimum speed. You did not get a ticket for going below the minimum you got a ticket for being dangerous.

    i am not sure how it is in other areas but unless traffic is non existent I go 65 in 65. I will NOT go over the speed limit (no matter what) but I also will not go slower than it. Where I live going slower than the speed limits around here is quite literally suicidal. When I go down 95 at 60mph (the ONLY road I go over the PSL of 55mph) I get passed like I am standing still going slower is begging to be killed literally.

    I hear people say but your going the PSL its not your problem THERE breaking the law. Well let me give you another analogy. There was this lady throwing a fit at a driver in a walmart parking lot for not giving her right of way. I look at her and say are you stupid or something? she says PEDESTRIANS HAVE RIGHT OF WAY (yelling at me)

    I turn around and point at the car and say 4000 pounds of metal and then point at her and say 200 pounds of bone and flesh. (I was being generous)

    I then yell YOU LOSE! everytime No matter what No matter who is right of way. 4000 pounds metal ALWAYS squishes 200 pounds of flesh. It does not matter who is right or wrong.

    Same applies on the highway. No matter who's fault it is its going to VERY MUCH be your problem when they THUMP you from behind because you were going slow enough that the speeding moron did not realize he needed to get out of your way.

    Drive ACTIVELY & AGGRESSIVELY DEFENSIVE. Thats how I drive. Good way to stay alive and minimize the hassle of having to repair a car regardless of who is at fault.

    NOW Road Rage. I have a very easy and so far 100% effective solution to road rage. STOPS raging drivers instantaneously. I pull out my camera and say Smile for my website jackass (if they can hear me)

    Its amazing how raging drivers INSTANTLY turn off when they see that camera (camera phones do not work needs to be a normal camera)

    I had this one guy. NO idea what I did to him while crossing the BBB into PA he was raging fuming mad at me (so I toyed with him off course occupied my time for a few minutes) anyway at the first light he was turning I was going straight. He stopped in the middle of the road and got out of his car to taunt me to stop with him. I obliged but off course only moron gets out of there car so I opened the door and said you want some of me? He gestured so I returned with a photograph and said Jackass of the Day *******! man instantly all anger left his face and he just RAN back to his car. It seems that the presence of a camera is like getting a wonk in the head. It STOP and STARTLES you back to reality and they realize what the hell am I doing :) in the dozen or so times I have done this (all over the country I do a lot of driving) it has worked 100% of the time and the results are instant. :) Its like an electric shock BAM turns off the rage.

    Just carry a disposable camera with you :) If you have an SLR style camera even better they think your a reporter or something. If you get some good jackass shots be sure to post them. With the guy above I laminated the 8x10 and affixed it to the traffic light. Someone (almost assuredly him) tore it down 3 times before I had enough fun and stopped pinning it up :)

    Don't be stupid. I am lucky in some ways I am 400 pounds 6'4" tall people tend not to mess with me but a gun is the ultimate equalizer. NEVER get out of your car. Thats a 3000-4000 pound weapon DO NOT hesitate to use it if the need arises. Squish first Ask Questions later (if fleeing is not possible) Never trade your veritable TANK for the flesh if your body by getting out of the car. Ever.

    First Post so be gentle :)
     
  6. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Nerys, are you interested in fuel economy?
     
  7. nerys

    nerys Banned

    Absolutely. Just not at the cost of safety. :) Ever.

    Here are my stats (all useless now with the stinking ethanol in the gas)

    I was averaging 24 in my cherokee (with 4" lift and 31" mudders) I am very good at squeezing mpg out of my cars. I am just finishing reviving my cherokee (452,000 miles on it!)

    My Voyager gets 24-28 though now I have trouble getting past 21 with the damned ethanol.

    My 300D is diesel and I can net 28-30mpg in the summer but only about 22-24 in the winter

    My Thing, Never got an accurate measure yet Once I replace the tranny I am going to find out.

    my 92 Clubwagon. Not even worth mentioning I only drive this for family vacations where it gets fantastic mpg only because it allows us to take ONE vehicle where 15mpg is better than two vehicles at 20-24mpg :)

    I have 2 of all of these. I always buy in pairs. so 2 vans 2 things 2 300D's and 2 jeeps. The second jeep is the donor engine to revive my jeep and I am going to sell one of the 300D's to allow me to bye a Metro (I NEED something that can reliably get over 40mpg without costing a fortune. I can get metro's for under $2k

    I have been using Acetone in the fuel which does seem to work at least enough to off set the detrimental effects of the Ethanol and brings my MPG back to pre ethanol numbers most of the time.

    I drive like a granny. Even acceleration (I have found that acc'ing too slow worsens mpg there is an optimal power band for economy without gauges though its hard to "hit it" reliably. Working on that but damned those scangauges are expensive and only my voyager can use them since all my other cars are pre 96 by a lot :)

    I definitely draft trucks if the opportunity presents itself. I do not go nuts 50-60 feet back which should still net a 30% reduction in aerodynamic drag while still being safe.

    Without real time feedback and no long term draft opportunities I have not been able to confirm any benefit financially so far.

    My ultimate goal is an electric car. The ultimate mpg is zero mpg ie NO GAS :)

    I have found that consistent driving helps more than trying to ultra tweak things (unless you have real time gauges) its the pulsing of the pedal or sloppy steering that really hurts things. I have rerouted my drive to work down too 2 left turns and fewer lights. I netted a 15% increase in economy by doing this even though its 4 miles longer :) (54mile commute each way so mpg is very important to me)

    I have gotten very good at driving arrow straight with no swerving or sliding (my dad says its freaky to drive behind me its like following a train :) although hard to nail down my yearly average has increased by at least 1-1.5mpg from this I estimate. Same with turning. Nice even smooth turns I will even swing a little wide if space permits since this reduces the momentum lost in the translation from one direction to another IE physical drag.

    I was seriously considering building a bubble butt for my minvan to reduce drag but I did the rough math and even if I keep the car for another 200,000 miles The cost of the cowl will never be equaled by the gasoline savings so I scrapped the idea. IE the same reason I will never buy a Hybrid. I would have to drive a prius 600,000 miles JUST to break even in gasoline savings. my 300D paid for itself in 11 months in fuel savings. Back when diesel was $2.69 it saved me about $90 a month in fuel and the car cost me $1200. I am trying to figure out a way of filtering waste engine oil affordably since if I can get the metal particles out I can dump it right in the fuel tank 50/50 with diesel and I can get a lot of waste oil cheap :)

    I also never every buy gasoline from Exxon, Lukoil or Chevron Especially Chevron. :) I will pay MORE per gallon rather than go to those.

    I am working on a way of removing my roof rack on the the voyager since the outlay would be $0 just labor and the drag reduction might give me a 1/10th of an mpg boost.

    I was also contemplating the potential of making my van a hybrid of sorts. I found out recently it WAS available as AWD. So if I can find an AWD rear axle and swap it in but connect it to an electric motor and small battery pack to reduce the acceleration load things could get interesting :) IE it might be possible to screw with that WITHOUT altering the existing drivetrain or components at all! IE I press a second "pedal" with my left foot to kick on the E motor to assist in acceleration.
     
  8. ma and pa

    ma and pa Active Member

    The Vermont Interstate system is not crowded compared to almost anywhere else I've traveled so I travel at 50 to 55 on the flat up to 65 downhill an 40 to 45 uphill unless there are many cars and trucks behind then I dont drop below 50. Ever notice that big rigs never get held up by you but when the road is empty there will inevitably be someone running up your exhaust pipe and they are on a cell phone. Jonathan
     
  9. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    That's a good start, Nervys -- though if you hang around here you will discover that there is only so far steady-state driving will take you.

    Acetone is not a good idea -- in small quantities it doesn't seem to really make any improvements in FE and in larger quantities the highly caustic nature of the substance can corode engine components.

    If you really want to make some large increases in your efficiency please read the articles found on the home page of this site (at the lower right) -- you can see a difference even without a SG and the techniques will cost you nothing!

    Welcome to the site and I hope you get as much out of this place as I have!!
     
  10. nerys

    nerys Banned

    That interesting. Do you have more info on acetone on the site here? I have shown marked improvements in mpg with it (your not supposed to add much in fact more than an ounch per 10 gallons makes mpg worse not better.

    Some time back I got freaked I filled up and my mpg sucked. I mean raelly bad drop in economy. 2 tanks in a row and then poof all back to normal. Then worse then normal. I was like what the frak is going on and then I noticed this STICKER on the fuel pump that said 10% ethanol. I started looking for it and noticed my "bad tanks" were at pumps with the ethanol. Well eventually they ALL had ethanol and I never got a normal mpg tank again. My Cherokee was still dead at the time so on a hunch I siphoned the gas out of the cherokee (With the tanks I have on hand I can store about 100 gallons of gasoline. IE enough to go 6 weeks if prices spike (this was before these insane prices that never go back down mind you) I think of it as a "price buffer"

    Anyway I used some of that gas which was about 7 months old IE pre ethanol (I use stabil to keep it good) and what do you know my economy went right back up to where it was!!

    I lost 14.5% of my fuel economy!!! When your going from 15+mpg to 13mpg in a Club Wagon that really really hurts!! So let me figure this out. We replace 10% of our fuel with ethanol to reduce out foreign oil dependancy but its so sucky that I am not buying 4.5% MORE fuel than I was before!! Grrrr I hate greedy politicians.

    Anyway I found this "octane" booster at a dollar store and while usually this stuff does not do much it appear to "offset" the effect of the ethanol almost completly (about 75%)

    Acetone does the same thing but even better almost 100% ie It brings my mpg almost back to what it was pre ethanol. I would definately like ANY links to information you have on acetone (pro and con) as I definately do NOT want to damage my vehicles.

    Steady State is all I can do right now because I do not have real time feedback as to the effects of any techniques and can not afford a scan gauge just yet.

    I hope to glean and if possible contribute information to this site. I visited many and this one apppears to be the only "really" active site forum around.
     
  11. desdemona

    desdemona Well-Known Member

    Depends on the amt. of traffic, so I couldn't really come to a conclusion on this one. It doesn't matter to me if there are others going faster, if I don't feel pressure from tailgating or close following or feel I am blocking the way based on looking around and seeing whether someone can get around me or not.

    I do think that some people are serial tailgaters. You see these clowns and they tailgate whether someone is going 55 or 75.

    --des
     
  12. nerys

    nerys Banned

    I come home from work at 3-5 in the morning so almost NO traffic. I usually set the cruise at 45mph and just let it ride. No hills minimal turns and only a few lights for this 35-40 minutes stretch of my drive. Save fuel and gives me a few more minutes to listen to podcasts :)
     
  13. lightfoot

    lightfoot Reformed speeder

    At that hour you're probably tired and cruise control is less work. But if you have the energy, pulse and glide will net you better mpg than steady speed. The idea is to use the ICE for pulses of energy to accelerate the car briskly (NOT wide open throttle, just briskly) and then let the ICE drop to idle and glide as long as you can (tires at max sidewall pressure will extend your glides). Thinking about just the frictional losses (and there are others), cruise holds the ICE at say 1500-2000rpm whereas idle lets it drop to say 700rpm. Why have the engine spinning twice as fast when you are drawing only minimal power from it?

    If you can work your pulses into rises and your glides into downhills, this works even better. Very few places in the US are actually completely flat. I would have sworn there were no hills in my commute until I started driving for mpg. There are actually lots of places where I regularly glide, sometimes for quite long distances, and I've learned to evaluate new routes this way. Your route may not have any major hills but there may be smaller glide-extender downgrades.

    Unless you can figure out a modification, I would not glide engine-off (FAS) at those hours. Because your lights will go off and on and that will attract unwanted attention from any cops along your route. Maybe test it out somewhere safe in the daylight before deciding whether to do some sort of engine-cut switch for regular use. Engine-off will net a bit more mpg but you have to be sure you know what your are doing.

    Are any of your vehicles manuals? Because if they are bump-starting is an option that avoids using the starter.

    At first all of this seems like a lot of work, and it is hard to do it smoothly so passengers (if any) don't whine. After a while, it gets instinctive and it's hard to drive any other way.
     
  14. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Along with that, be sure that any automatic transmissions you may have are "flat towable" (you can pull them on all 4 wheels) -- the owner's manual should let you know if they are. If they can't be towed that way, don't FAS them. This has to do with the way that the transmission is lubricated -- if it is lubed by an engine driven pump you'll run the bearings dry while coasting engine off if it is any reasonable distance. Not good!!

    Manual transmissions are just "splash" lubed -- as long as the gears are moving they are getting lubed, engine on or off.

    I suspect most if not all of your transmissions are manual?
     
  15. nerys

    nerys Banned

    OK I need someone to clarify this pulse and glide to me. First let me desribe what I THINK it is and how I would imagine using it and what I think your describing (because what your describing seems very INEFFICIENT to me) so either I am misreading what your saying OR I have no idea what pulse and glide means.

    Without having much knowledge in this specialized category I am using my knowledge of aeronautics to discuss this which might be why this is unclear to me.

    To get to a destination in the most expedient manner you would thrust at max thrust for precisely 50% of your journey and they reverse thrust at max thrust for the other 50% of your journey. Your max velocity is explicitly limited by the distance to the 50% mark not counting a safety margin or thrust limitation.

    Now in cars this is irrelevant since our max acceleration is actually pretty low AND our brakes can decelerate us as a much greater rate than out throttle can accelerate us.

    Now not counting brakes we have 3 things slowing us down. Drag x 3. Aero Drag. Friction Drag with the ground and Friction drag with our internal moving components (engine transmission axles wheels bearings etc..)

    When I think pulse and glide I am thinking ok I have a destination in front of me and I want to accelerate as little as possible without wasting energy. If you have to use the brakes you are bleeding potential energy kinetically into you brakes IE heating them up.

    If you coast completely to a stop you have utilized the maximum amount of energy in return from the potential energy you created by accelerating. Now there are practical limits to this. One pissing people behind you off big time if you really take it to an extream and ignoring FAS at a certain speed you start to once again loose efficiency since your engine is still running.

    NOW this should work quite nicely for decelerations to stops lights turns etc.. (mines an automatic so I won't be doing any FAS action but I have started to neutral cruise especially on grades and full stops.

    NOW I think I got it so far. Your above statement is what confuses me.

    What you describe above is overunity and should be impossible. IE using pulse and glide on regular flat straight runs should always be far less efficient than steady state.

    Sure when you glide your getting amazing mpg but your going to lose it all and then some when you "pulse" again.

    the only way for this to EVER be more efficient (at least as I can see) is if your GETTING energy from somewhere outside your immediate mechnical system. IE going downhill for example. Your now taking energy from the earth gravitationally.

    This only really works if the "grade" is large enough to propel your car without loss of speed with the transmission disengaged. Even then you gain nothing (you spent that energy to climb that grade) you are not gaining energy but simple reducing how much energy you LOSE. ie increasing efficiency.

    Gliding does not use less energy it just uses that same energy to move you a little further instead of simply heating up your brake pads. IE again more efficient.

    Have I got the jist of that? IE what am I missing?

    On my the rt 206 portion of my drive there are only 5 lights for bout 40 minutes of driving and I almost NEVER have to stop or even slow down at any of them. Except for the single primary intersection I can see all of them from enough distance away to adjust my velocity to time the approach to eliminate the stop. Thankfully no smart lights so they change regularly. When I go to the campground in the summer there is this one stinking light that I have to stop at 100% of the time because it NEVER turns green EVER "unless" there is a car AT the light. IE its always red UNTIL you stop at it and then and only then it changes to green. Grrr I hate that light. :)

    SO how can pulse and glide do anything for me on a straight no stop run? Gliding only seems effective to me at making use of energy you would otherwise burn into the brake pads.??
     
  16. lightfoot

    lightfoot Reformed speeder

    What you are missing is the efficiency of conversion of chemical energy in gasoline into kinetic (or potential) energy of the car. You have to look at the thermodynamics of the entire system. Constant speed considers physics only and does not take into account the characteristics of the ICE. If you are at constant speed, the ICE is running at a small throttle opening, which means it is running inefficiently and also that the frictional losses in the ICE are constant.

    In terms of overall efficiency of conversion of gas to moving your car a distance, the net result is better if you burn a larger amount of gas for a short period of time (and convert it more efficiently into kinetic energy) and then burn no gas (ICE off) or a tiny bit (ICE at idle) for a longer period of time while you glide.

    See the articles section here for a further explanation. You don't glide to a complete stop (unless you have to stop for some other reason). You P&G over a speed range (say up to 55 and then down to 45). The target values can be shifted to help avoid angering traffic following you on roads where they cannot pass easily. Brakes are not used in P&G.

    I was skeptical too until I tried it. It helps a lot to get a ScanGauge so you don't have to run through most of a tank to get the data.

    As far as aero drag goes, we try to operate below the speeds where aero drag is a major factor (i.e., 50mph or slower).
     
  17. nerys

    nerys Banned

    Hmmm I had always assumed the engine at low near idle speeds was much more efficient than ANY acceleration RPM. That is interesting. That seems all mute if you do not know at WHAT RPM your engine is most efficient. How does one determine this? ie acc too hard and your burn away your gains etc.. Might definitely give that a try and see what happens. I could easily screw with it one the way home. Many times I an go 20+ minutes without seeing another car :)
     
  18. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Nerys, while it is true that you should have some feedback to figure out the ideal acceleration rate for most vehicles it is between 2/3 and 3/4 full acceleration rate. You don't want to full out lay the pedal all the way as far as it will go but do accelerate "briskly."

    You can do this without any feedback system at all if you'll pick a decent rate as described above but you do need a gauge of some sort to figure out the ideal rate. The ScanGauge can do this by showing your average. If you pick a known route and try several different rates you can reasonably compare the average FE (mpg) across the entire segment with different rates to see which one yields the best result. Try 2/3 full acceleration rate and you shouldn't go wrong with that as long as you have a good delta to work with. 10mph is pretty good (as suggested by LightFoot), but 15 seems to yield really good results for me.

    As LightFoot mentioned, you can also vary those setpoints in speed to deal with traffic situations. Hypermiling is a very fluid activity constantly adjusted for terrain, weather, traffic, and road conditions. :)
     

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