"National speed limit pushed as gas saver"

Discussion in 'Legislation' started by Steve_O, Jul 4, 2008.

  1. hobbit

    hobbit He who posts articles

    You're on very thin ice. Safe, "reasonable" speeds would be
    much higher *IFF* everybody actually gave each other decent
    following distance. As things stand now with as close as cars
    generally seem to get, I'd say a safe speed in that ratpack is
    about 35 MPH. You *cannot* determine your percentile from that
    sort of situation, it's just pathologically, hopelessly unsafe
    for 55 or anything in that area until these numbnuts *back off*
    from each other.
    .
    _H*
     
  2. Ophbalance

    Ophbalance Administrator Staff Member

    I wonder what would happen if, instead of MPH limits, we set minimum MPG limits? That'd ruffle a crap load of feathers. It also shoots the 70 minimum in the foot. I do own a newer vehicle (06 Sedona), and it still gets its best mileage in the mid 50s. Until we start making cars that get good mileage (and by good, I mean in the 60 MPG range) at anything over 65, it's just irresponsible to think of setting the limits any higher.
     
  3. anon

    anon Well-Known Member

    Agreed.


    People aren't packed in closely because they like it OR feel it's safe. They're in tight because our road capacity can't handle the traffic.



    Back off, or pull away. Either one is fine for increasing following distance, but neither can be achieved with a 55 mph limit.

    Either CAN (and would) be achieved if we had highways that could handle our traffic.

    My dream of more lanes is not likely to be realized. :(
     
  4. hobbit

    hobbit He who posts articles

    >> neither can be achieved with a 55 mph limit.
    .
    Huh? You can achieve three or more seconds of following distance at
    any speed. Four or five leaves plenty of room for new cars to merge
    in and re-establish distance, too. Like I do all the time in the
    oft-fabled "directed malice" of Boston traffic.
    .
    See the traffic waves articles.
    .
    _H*
     
  5. Wolv60

    Wolv60 New Member

    National speed limits are flawed in the sense that manufacturers gear cars for optimal performance at varying speeds. I belong to a group of LS4 engine owners and our engines are designed to shut off cylinders at under 8% throttle. We've all been tracking mileage on the highway and found that 61-65 mph is a sweet spot for our cars. Most people have gotten 28 mpg right there, with a few lucky people breaking into the thirties. If we slow down it down to 55 mph we see a drop down to 25 mpg. Whereas in a my old Saturn sedan, 55 did yield better mileage than 60. It depends on what you drive.


    A much more logical solution is to shift traffic enforcement to cover tailgating, weaving and other habits that require frequent braking. Everytime I hit my brakes on the highway I waste gas, the gas I used to get up to speed and the gas I'll use to get back up to speed. Having the police clean up the flow of traffic would got alot further than setting an across the board speed limit.
     
  6. fixedintime

    fixedintime Well-Known Member

    I would think a lot of manufactures have two goals in mind as they decide on their FE curve. The first is designing to the test. They want the numbers for their car to look good on the EPA test. So they are going to design their FE curve to get the best results on the tests that are given. This will be more so as the emphasis comes to be more and more on meeting some magic fleet mpg figure.

    Secondly they don't want their customers to be too unhappy at the perceived performance of the vehicle. So as long as the design does not too adversely affect the EPA test results they are going to head that direction. That usually gets translated into acceleration as much as anything else.
     
  7. lamebums

    lamebums Member

    With regards to the varying mileage at higher speeds, all I can say is to have a 5 speed manual with tall gearing and a lot of torque down low and it will work wonders for mileage. :)

    I just say we enforce the speed limits as they are now--in other words, no blasting down the road at 85 MPH and getting a warning. 65 means 65. It's the law.

    And then have cops focus on aggressive drivers--tailgaters especially. Idiots going fast in the slow lane should also have a bullseye on their backs.
     
  8. A024523

    A024523 Currently in Training

    Good point, they are very laxed about enforcing the current law. If the limits are lowered to 55, and they don't enforce it, what good is it. In California, they do "zero tolerence" enforcement, but only for a couple days per year, and they actually announce it. :rolleyes:
     
  9. smacky

    smacky Member

    I think that before we lower speed limits we need to figure out how to enforce the current speed limits. They are 65 where I live but I would estimate that no more than 20% of highway drivers observe the speed limit.
    In my younger days I always appreciated it when the highway patrol would only cite me for 10 over when I would be doing moch more. But it's created a lack of respect for the rule of law. I think officers should more aggressively cite speeders, perhaps for doing as little as 5 mph over and should cite drivers for the full amount they were speeding.
    It's not just about the gas that they are paying for. Faster freeways kill more people.
     
  10. hobbit

    hobbit He who posts articles

    It's really trivial to spot many of the more aggressive ones
    on the freeway -- they're the ones always flicking their brake
    lights as they desperately try to avoid crunching the backside
    of the poor sod they're tailgating at .25 second. The cops
    could just pick them off one by one and have a HUGE revenue
    source -- that's the "self-funding" aspect of my hack piece
    urging more on-the-fly enforcement via dashcams. Ten seconds
    of video and the butthead is toast.
    .
    _H*
     
  11. jcp123

    jcp123 Caliente!

    I don't know that I'm for a 55 speed limit, but I'm not positive I'm against it either...maybe 60, or as in California, 65?
     
  12. kelly.cardona

    kelly.cardona Well-Known Member

    Same here.
     
  13. JusBringIt

    JusBringIt Be Inspired

    50 min..how about 40 min 60 max? I would go for that.
     
  14. Shiba3420

    Shiba3420 Well-Known Member

    Let me throw a wrench in the works...if there were a national limit, should it take effect right away, or a few years in the future?
    It would be a real shame if someone bought a car this year which was geared for best fuel performance at 60/70mph and then drop the limit to 55...suddenly these people would be getting less than their best.
    I wish EPA stickers incluced a graph showing what mpg a car gets (under control circumstances) at every speed from 5 to 90 mph.
     
  15. gfdengine204

    gfdengine204 Well-Known Member

    I, too, would be in favor of such an animal.

    How about an imposed national 55MPH limit, with no press about it. The for the first few weeks, we divert the revenue from speeding citations to push for less foreign oil dependency?

    I'm kinda kidding......kinda. :rolleyes:
     
  16. Ophbalance

    Ophbalance Administrator Staff Member

    I know of few cars, excepting perhaps sports cars, which are geared for their best FE in that range. So, I guess that I fail to see the point...
     
  17. A024523

    A024523 Currently in Training

    You're right. From all analyses that I have seen on this site, as well as, many other sites, including the EPA, optimal FE is achieved well below 60 MPH for most vehicles. Here's a good thread with stats/charts on it...
    http://www.cleanmpg.com/forums/showthread.php?t=10986
     
    Last edited: Jul 15, 2008
  18. bear15

    bear15 Well-Known Member

    This would be interesting to see, however....


     
  19. Shiba3420

    Shiba3420 Well-Known Member

    Yep that a great thread and make sure to check the traffic simulator posted near the end.

    My only problem is the graphs can't be (completly) right. With the automatic cars, there should have been a sudden increase in economy when the car shifted down, but that itsn't seen. Another graph that shows economy at a fixed speed and different gears/rpms, verfies that the upper gears should show an economy improvement. One or the other has to be wrong, and from experience I'd say its the speed/mpg graphs. They are generally correct, but either some info is missing (like entire test in a forced single gear) or the data points were too far apart & the graph curve smoothed out.
     
  20. A024523

    A024523 Currently in Training

    Jonathan, your right regarding the data does not cover nearly all bases. I think the EPA ought to provide MPG data at different speeds for each vehicle, so that consumers can have vehicle & speed specific MPG information. I am sure there is at least some variation in optimal FE speed for every vehicle and transmission type.

    PS - That simulator rocks! http://vwitme011.vkw.tu-dresden.de/~treiber/MicroApplet/
     

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