• Aug 25th 2007 at 1:46PM
  • 29


Everyone's probably familiar with the idea that engines in cars produced today are tuned to burn gasoline most efficiently when the car is moving at about 55 mph, right? I thought I'd heard that some newer cars were tuned for a slightly higher speed (60 or so), but I haven't been able to confirm that. Anyway, the point is that cars do not run their best at 70 or 75 miles per hour.

Nonetheless, most of us don't drive 55, even in areas where that's the speed limit. Some young people in Atlanta decided to commit an "act of civil obedience" and enforce the 55-mph limit on a busy Atlanta-area highway. Let's just say the people behind the 55-mph drivers were not happy, as the video above shows (I wish the kids put as much time into editing the clip as they did with the stunt itself).

Anyway, this video came to our attention thanks to a reader who uses the event to think about whether or not cities should be sending out fleets of cars to do what the young people in the video did. Ticket-enforced speed limits obviously don't make people drive 55, and knowing that you're emitting more than you would at a lower speed doesn't do the trick, either. How important is it to go 55? If you're interested, you can read the full argument in favor of enforcing the limit. What do AutoblogGreen readers think; should we consider the community at large and work harder to make 55 mph the speed people actually drive? Or is 70-75 the right highway speed, and we should push automakers to develop engines that are more efficient at that level? Will EVs make this entire debate moot in two decades' time?

Finally, I think it's only fair to put Sammy Hagar's preemptive response to this idea after the break.

[Source: YouTube h/t to ]


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  • 29 Comments
      • 5 Years Ago
      I rewrote Sammy Hagar's song in perspective with the car I drive, which is an oil burning gas sucking land yacht with bad tires and loose suspension bits that wobbles from 55-65 and burns so much oil above 60 as to create a fog behind me. So I drive 50, because it would be inconceivable to drive 55 or above in this death trap.

      Bluehair Hagar -"I (Still) Can't Drive 55"

      One foot on your brake, and one on your gas, hey!
      Well, the shoulder's too narrow, you can't pass, no!
      So you try it on that double yellow
      and a passing grain truck made you mellow, again

      Go on and cuss me out for doin' 45
      Know that I'm the slowest driver alive
      Your fast car and freedom I will deprive
      I can't drive...55! Oh no! Uh!

      So I tried last week to go 54, hey!
      Yeah my oil pressure light came on once more!
      I'm gonna slow my ass to a grandpa's pace
      Look me in eye eye and I'll smile to your face
      saying Yeah! Oh yeah!

      Cuss me out for doin' 45
      Know that I'm the slowest driver alive
      Your fast car and freedom I will deprive
      I can't drive...55! Oh yeah!

      Just because I'm this slow doesn't mean I fear, no!
      I'm happy at my speed and I'll stay right here!
      I got a 30 gallon tank I can do this this all day
      Nothing better for me to do than get in your way!

      Cuss me out for doin' 45
      Know that I'm the slowest driver alive
      Your fast car and freedom I will deprive
      I can't drive...55! (etc etc)

      If you like this rewrite, send new and unopened bottles of 40-weight API SL rated oil to:

      Occupant Ilied Industries
      Malone, TX 76660
      • 8 Years Ago
      Yah, the math behind this is sort of complicated, so the program I work on had to get a doctor of physics to do the math for us. If you want see the formula (it doesn't cut and paste in) it's here - http://drivewiser.ca/default.asp?mn=1.181.184.207 .

      The basic principle behind it is that with a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as quickly. Since power is the rate of doing work, four times a work in half the time requires eight times the power.
      I dunno about 'merican miles, but in km/h this works out to 150km/h uses 125% more fuel than 100km/h. So you travel 100km, you're only going to be shaving 15 minutes off of your time but you'll be using more fuel that it would take you to get there an back again.
        • 7 Months Ago
        The link you provided doesn't work. Is it just their mileage calculator?
      • 8 Years Ago
      They should come to Dallas and try that... I can see a different outcome from camera the bridge.
      • 8 Years Ago
      This happened last year didn't it?
      • 8 Years Ago
      The point here is ENFORCE or ABOLISH. To selectivly enforce is unfair to everyone.

      I'm thinking immigration...
      • 8 Years Ago
      Couldn't agree more with comment #3. How many times have you seen this useless attempt at parenting: daddy or mommy repeatedly screams "stop it johnny" while the brat's behavior only worsens. Unenforced rules only serve to weaken authority.
      • 8 Years Ago
      Read about a similar incident (involving fines!) in Canada.

      http://freerepublic.com/focus/f-news/678348/posts
        • 7 Months Ago
        Rolling roadblocks, obstruction of traffic, or whatever you want to call it is illegal in almost every jurisdiction.

        Don't even try it when approaching a construction zone where douchebags refuse to merge (or even slow down much) until the last moment. It's a ticketable offense to impede traffic by hanging out in the fast lane going slowly. I saw police officers stopping at least two truckers and a few car drivers over the course of a week where there was an especially long "merge soon" warning zone before the actual merge point.
      • 5 Years Ago
      Joe's got it on the air drag varying as V^2, and that power moves that relationship to V^3 (Drag being a force, and Power being Force x Velocity). Add to that the fact that power dictates fuel consumption (almost directly, although in 'real world' cases, there is some variability) and the result is that fuel consumption grows at the rate of V^3. As such, going 70, in any car, requires more than twice the Power required to go 55. This result is requiring 60% more fuel per mile (2.06/(70/55))
      • 8 Years Ago
      In some countries (like the Netherlands) police "pace-cars are used (tested) to slow down traffic or to keep the traffic at a sustained speed... this prevents many traffic jams... and by preventing jams, you save gas.

        • 5 Years Ago
        Actually, pacing traffic with police cars or motorcycles is done more widely in Belgium.

        The Netherlands enforce average speed limits over sections of highways by scanning license plates at one point and again a few miles later. If your average speed is below the limit the data is deleted, if the average is above the limit you'll get a ticket.

        I've heard rumours that something similar happens on toll roads in France, calculating your average speed between toll booths, but correct me if I'm wrong.
      • 8 Years Ago
      Don't forget that a lot of energy is spent accelerating/decelerating the car linearly as well as each rotating part. Cars have way too much power to drive at legal speeds but they need it to get there. People want zippy cars you know...
      • 8 Years Ago
      "Don't forget that a lot of energy is spent accelerating/decelerating the car linearly as well as each rotating part. Cars have way too much power to drive at legal speeds but they need it to get there. People want zippy cars you know..."

      Sounds like a perfect argument for hybrids, actually, which was their original business case. A small efficient ICE that's optimized to produce just a little bit more power than is necessary for highway cruising, combined with a potent electric motor that's optimized for brief bursts of torque and is recharged over time from regen braking and that slight available overpower on the highway.
      • 8 Years Ago
      What a bunch of drama queens.

      Just get in the right lane and do 65.
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