[Keith_McClary]

driving at 55 mph versus 75 mph can save up to 23% of fuel

So, assuming that is a linear increase in consumption from 55 to 75, and given my car's mpg at 55, and assuming my time is worth $X/hr and gas is $Y/gal, I can calculate the optimum speed.
Maybe tomorrow I will do the math.

[ralfy]

Kurt should really be on the board of ASPO International instead of a the local lobbying group so he can give those Parisians a what-for.

Not necessary:

http://peak-oil.org/2012/08/commentary- ... c-reality/

[ROCKMAN]

pstarr – “So the faster we go, the more likely it is that we will miss that traffic jam.” Not only that but the faster we drive the quicker we can get to our destination before we run out of gas.

[Ibon]

People are speeding because we build roads that allow people to drive fast. If we stopped maintaining our highways and leave a bunch of pot holes around and tear down the fences so that livestock can roam along the sides of the road people would slow down. Removing the shoulders from the side of the road would help. There would be more scary accidents. Higher death tolls. This would reduce speed and greatly increase fuel efficiency.

What I just described is the state of most of the roads here in Panama. I don't see anyone driving faster than 50mph.

[C8]

Here is another reason for speeding, really way out there, but I will say it anyway.

I don't think Americans really believe in this "heaven thing" that they hear in church. In the back of their minds they are thinking: "no, this world is all there is" so they are always trying to get the most out of each moment because they believe there isn't really anything after death. So we speed to not "waste time" because this life is all we will get. I have found that really spiritual people, generally move at a more relaxed pace since they believe they will always be around in some form. Many atheists I know who are at peace with their fate seem pretty mellow too.

In other words, speeding is a sign of fear.

Like I said- this theory is really out there

[ROCKMAN]

Sadly I'm speaking from experience also. I can remember 2...maybe 3 conversations with folks who actually believed driving faster was the best way to get where they were going before running out of gas. I still ca'n't get my wife to accept tha ceiling fans don't actually lower the room temp. You would think a Yankee would understand windchill better

[Tanada]

Sadly I'm speaking from experience also. I can remember 2...maybe 3 conversations with folks who actually believed driving faster was the best way to get where they were going before running out of gas. I still can't get my wife to accept that ceiling fans don't actually lower the room temp. You would think a Yankee would understand windchill better

Careful ROCKMAN, or she will be giving you the cold shoulder!

[Ibon]

A wise man once said that those driving fastest on the highway are those who aren't happy about the place they just left or the place they are going to.

Racing to nowhere......

Another wise man once said that the definition of a modern human is one whose adrenalin is firing without the accompanying muscle exercise.. I would say that applies to most fast drivers...

[Keith_McClary]

... assuming my time is worth $X/hr and gas is $Y/gal, I can calculate the optimum speed.
Maybe tomorrow I will do the math.

OK, I did the math.

Suppose you are paying someone $R/hour to drive and you are also paying for the fuel (assume no other expenses). You don't care how long the trip takes.

If fuel is expensive you would want to stay at the Sweet Spot speed. If it's very cheap you want to go faster to minimize the payroll. For intermediate fuel costs there is an optimum speed that minimizes cost of the trip. I get the approximate formula (good near the Sweet Spot):

E = 0.63 R/C

where:
E = optimum increase of speed (above Sweet Spot speed).
C = fuel cost per unit distance at the Sweet Spot.
The (dimensionless) number 0.63 is essentially the curvature of the graph at the Sweet Spot.

For example, if C = ($25/gal)/(25 mpg) = $1/mile and R = $10/hr then
E = 0.63($10/hr)/($1/mile) = 6.3 mph.

If fuel is "only" $4/gal then E is about 40 mph (the formula is inaccurate at these values).

My conclusion is that fuel costs would have to be several times higher before the cost of driving faster exceeds the the value of the drivers time. So that's another reason they speed.

[dolanbaker]

... assuming my time is worth $X/hr and gas is $Y/gal, I can calculate the optimum speed.
Maybe tomorrow I will do the math.

OK, I did the math.

Suppose you are paying someone $R/hour to drive and you are also paying for the fuel (assume no other expenses). You don't care how long the trip takes.

If fuel is expensive you would want to stay at the Sweet Spot speed. If it's very cheap you want to go faster to minimize the payroll. For intermediate fuel costs there is an optimum speed that minimizes cost of the trip. I get the approximate formula (good near the Sweet Spot):

E = 0.63 R/C

where:
E = optimum increase of speed (above Sweet Spot speed).
C = fuel cost per unit distance at the Sweet Spot.
The (dimensionless) number 0.63 is essentially the curvature of the graph at the Sweet Spot.

For example, if C = ($25/gal)/(25 mpg) = $1/mile and R = $10/hr then
E = 0.63($10/hr)/($1/mile) = 6.3 mph.

If fuel is "only" $4/gal then E is about 40 mph (the formula is inaccurate at these values).

My conclusion is that fuel costs would have to be several times higher before the cost of driving faster exceeds the the value of the drivers time. So that's another reason they speed.

Yes I concur; I frequently do a 120km journey to Dublin and I usually drive at about 95-100kmh and the average fuel consumption is 6.2l/100km, the same journey at 120kmh consumes 7.5l/100km almost €2 extra fuel to save 30 minutes.

My pay is considerably higher than €4 an hour.

[kublikhan]

And whatever happened to hypermiling? During the first price shock of 2008, stories abounded of people who had perfected a gas chiseling driving style that boasted savings of up to 40% by methods such as gradual acceleration, drafting closely behind trucks, etc.

Some of those hypermiling tips are dangerous. Drafting trucks, removing your side mirrors, overinflating your tires(and thus increasing your braking distance), blocking your radiator, etc. Let's not forget we are driving in those same collapsible boxes. Of course driving slower such as slowing down from 75 to 55 will save you fuel so I am all for that tip. But don't sacrifice your safety to eek our a few extra miles per gallon!

Not to mention some of the tips promoted by hypermilers are counter-intuitively wrong, like gentle acceleration gives you better mileage than rapid acceleration. The low gears of your car are the most fuel inefficient gears of your car. And to increase the time you spend in these gears with gentle "pretend there is an egg under your foot" acceleration is a surefire way to drag out the amount of time you spend in these low gears and ruin your fuel economy. Tests show normal-rapid acceleration has better fuel economy than dragged out acceleration.

I made three runs using each method, alternating methods to try to avoid any changes due to other factors.

Rapid acceleration to cruising speed is more fuel-efficient than slow acceleration. Presumably the greater fraction of the drive spent in high gear at cruising speed more than makes up for the hard acceleration.

Acceleration mini-experiment

[Tarrel]

Gas being more expense than it used to be is not the same as gas being high priced. Even at $4 a gallon, its usage in typical vehicles isn't even the majority of cost/mile.

Gas was extremely cheap.
Gas is now just very cheap.

Get back to me when gas is $20/gal [US$2013].

Yep, try getting someone to push your car 30 miles for $4!

[dolanbaker]

Gas being more expense than it used to be is not the same as gas being high priced. Even at $4 a gallon, its usage in typical vehicles isn't even the majority of cost/mile.

Gas was extremely cheap.
Gas is now just very cheap.

Get back to me when gas is $20/gal [US$2013].

Yep, try getting someone to push your car 30 miles for $4!

Not only that Tarrel, but let's imagine that we are an American fabric manufacturer like Versace or Dior who depends on Indian cotton. That poor family growing OUR cotton only needs one gallon/week of diesel to pump his shallow well. But that $2.00 weekly extra outlay accounts for 25% of his income.

Oops! There goes the kid's gruel. And our skinny jeans.

It won't happen like that, if Rajiv can't afford petrol to get to work, he'll stop going. That is bad news for the factory owner, so he'll get a pay rise sufficient to enable him to afford to get to work and pass the extra cost directly on to you (the customer). It makes no odds to him as he'll still make the same amount of money from Rajiv's labour.

[John_A]

Gas is high priced, but that doesn't mean the rate at which we consume it driving has stayed the same at all

Once upon a time I drove 55mph and achieved 18 mpg for my efforts.



Nowadays I drive 80-85 and achieve 43 mpg.



You CAN have your cake and eat it too!

[vision-master]

300 horses under the hood, did a 400 round trip to the brothers place a couple weeks ago - average MPG (32 mpg). Drove 5 mph over most of the way, 60 to 75 mph depending on roads.

Can't wait for those 3.2 L V-6's (supercharged) coming out with 8 speed autos, should have around 350 hp and I'm betting MPG will be closer to 35 mpg.

Then again, maybe it will be time for a 2.0l TDI (I'm not a fan of VW) too much money for what you get.