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by A bill mandating a 35mpg standard for motor vehicles by the year 2020 just passed Senate approval on Tuesday. The measure was naturally received was distress by automotive manufacturers (including Toyota), claiming the technological requirement curve was too steep. If America were really serious about reducing oil dependence immediately, congress should reintroduce a national speed limit of 55mph as they did thirty years ago during the 1973 oil crisis. Empirical evidence has shown time and time again that reduced speeds equate to a dramatic increase in miles per gallon.
Fuel economy is typically determined by testing in laboratory conditions standardized by the EPA. Interestingly, the testing is for engine emissions compliance from which fuel economy results are derived. Generally speaking, developments in reduced emissions and improved efficiency go hand in hand with the OBD system, but that is not always the case. A more complete burn of gasoline results in increased hydrocarbon emissions. The OBD II systems in modern cars are a result of environmental pushes in the late 1980s to reduce hydrocarbons. This is why the miles per gallon metric stagnated through the 1990s; automotive manufacturers were more focused on meeting lower and lower emissions standards than improving fuel efficiency.
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Looks like some scientists have made "intelligent" cars that feed on a network of traffic data. Essentially, the vehicles predict slowdowns for either traffic or red lights and bring the car to a more gradual stop. This eliminates much of the stop 'n go waste that eats so much fuel allowing a standard car to achieve hybrid-esque fuel efficiency performance.
This looks like the "forced" application of improved driving habits - just more proof that our oil dependence is a result of our own laziness.
I think this all depends upon the car. My daily commute is a straight line from my house to my office, with only a single stop between for a distance of 22 miles. The speed limit is 45 mph along the road and I use cruise control. I drove this for one week, taking no side trips (unfortunately, I don't have the luxury of the gadgetry that Vnut used in his Jeep.); and I used 9 gallons of gasoline. This is actually more than it takes me for the round trip to pick up my pair of rowdy outdoor loving youngsters in Wilkes-Barre PA--where I average 70-75mph on the road. The distance door to door one way to 147 miles; and a round trip actually only takes 8 gallons. I also use cruise control for most of this trip as well.
I drive a 2005 Classic (Malibu--the Classic was the version released to rental car companies, with the 2003 body style) which according to here should get between 25 and 34mpg. I average about 23.7 during the week going to work and side trips to lakes, rivers, and streams for fishing and getting outdoors and about 31 on the round trip to Wilkes-Barre.
This isn't very scientific, it's only anecdotal, but it certainly looks like my fuel economy is better going to Wilkes-Barre. On that trip, I actually have to go through York, so I spend 25 minutes hopping from stop light to stop light until I hit the interstate.
Commuting is a major problem with regard to fuel use in this country. The lack of decent and available (one system near me is cutting services and raising prices) public transportation, the distances people drive for affodable housing (or just because we happen to like our community). I think this problem needs to be addressed in addition to increasing fuel efficiencies. In another post I cited this article about ethanol where a scientist from Berkely calculates that by doubling fuel efficiency of vehicles would decrease our oil needs by 33%. If we add public transport to the equation, return to the days of using trains for long haul, and trucks for short runs; then I think we could be out of this in a short time. 35MPG is a good start, but I think we can accomplish this by 2010; we don't need 13 years.
Combine all of this and throw in alternative fuel research. It's time we run to the forefront; and cut our energy use, without sacrificing our recreation or our quality of life.
As another note--Vnut I can certainly tow a much larger payload in a Suburban or a Tahoe than I can in a Minivan. And carry as many passengers. But then, I like boating and camping and fishing; so I would like that ability. I don't own an SUV, and certainly wouldn't drive one to work (unless it were like my car and got close to the same or better fuel economy).
Although, for around the town use, why not a Golf Cart during daylight hours? South Carolina law permits use within 2 miles of your home on secondary roads. Believe me, they take advantage of this in Myrtle Beach; you should see some of the carts they sell. I intend to buy one when I move down there.
Believe me, they take advantage of this in Myrtle Beach; you should see some of the carts they sell. I intend to buy one when I move down there.
Yeah - my parents live in Murrells Inlet (just five or ten miles south of Myrtle Beach on 17). There's a lot of weird stuff down there - to include a taxi cab service using imported British cabs for "the look". Plus you get the annual Bike Week crowd.
The sweet spot is definitely different for different cars - owing to gearing and aerodynamics. I think there is a nexus between an efficient fuel burn and actual engine efficiency. For example, most engines operate best at high RPM (the Jeep achieves maximum horsepower/torque around 5000). This is also why 0-60 runs are done in low gear at high revolutions. While the engine operates best there, it also eats up fuel. But you also get 0mpg by idling at your lowest RPM and not moving. So what we get is this "window of efficiency" where most vehicles work best. In your case, it may be that going slightly faster bears an extra burden of wind resistance, but the higher RPM equates to more horsepower to force through it at an optimal engine setting.
Regardless, though, the sweet spot is not 75mph for SUVs and most other vehicles!!
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legislation is not always the answer by Anonymous :: NR0 :: on 09 May 2007
part of the problems associated with making engines fuel-economical is that the EPA continuously changes the rules for compliance. it takes time to engineer in accordance with a standard, and the changes to the rules hurt the businesses. while IANAEE (engine engineer), my dad is one, and this is one of his major gripes.
regarding the speed limit change, i am extremely skeptical of that step. how effective would it be, especially when compared to the cost of the step? speed limits ought to be about safety (which is a completely different topic - i am for the abolishment of our current traffic laws and the institution of the german laws). are there other steps that would better help our short-term consumption of gasoline? how much of our consumption is due to speeding, compared to sitting in traffic or flying? how effective would it be anyway, considering the majority of the population thinks speed limits are too low. there is already an economic incentive to drive with fuel economy in mind - do we want to have our police forces out giving ridiculous tickets as an additional incentive? and what is the cost in labor for having people sit in traffic longer and take longer to make their trips? i'd like to think my time is worth spending an extra couple bucks on a trip - at least that's what my employer thinks.
incidentally, cruise control and a 55mph limit would probably get worse mileage than someone with a flexible speed in hilly terrain. there's nothing more wasteful than hitting your brakes while going downhill just because john-law is waiting to treat you like a criminal, and then punching it to maintain the speed when going back uphill.
perhaps the gov't ought to outlaw off-road vehicles, like jeeps, with their non-aerodynamic light bars and canoes. =)
RE: legislation is not always the answer by VnutZ :: NR8 :: on 09 May 2007
part of the problems associated with making engines fuel-economical is that the EPA continuously changes the rules for compliance.
Completely agreed. There was an article I read on-line (which I can no longer find) three years ago when I was learning about OBD that detailed the stagnation of fuel efficiency because of environmental concerns. There was a distinct period in the 90s where vehicles were less efficient than their 70s and 80s counterparts because the movement to reduce smog and noxious emissions was overrode all else. Playing to environmentalism is an easier banner for a politicians to wave because it looks good now and failures will come years down the road during another administration's reign. All the while, like you said, American engineers are faced with redesigning to meet the latest specifications.
regarding the speed limit change, i am extremely skeptical of that step. how effective would it be, especially when compared to the cost of the step? ... what is the cost in labor for having people sit in traffic longer and take longer to make their trips? i'd like to think my time is worth spending an extra couple bucks on a trip - at least that's what my employer thinks.
So let's use the speed graph from the Improve MPG: Factors Affecting Fuel Efficiency article. Essentially, the difference between 55mph and 75mph is nearly double the amount of fuel (3.78 units per time vs 6.65 units per time). Now assume you're driving 1000 miles. At 55mph, that will take you 18 hours. At 75mph, that will take you 13 hours. Using the fuel multipliers, 55 mph "costs" 68.72 units of fuel while 75mph "costs" 88.66 units of fuel. So there really is no argument that driving faster saves gas because the engine is running for less time. Running an engine for five extra hours in a more efficient manner uses 23% less fuel!!
To your point, though, time is money and money drives business. So the application of this question is whether or not getting to your destination is worth it. For shipping and transportation? A business saves money in overhead (and can do the Wal-Mart thing and make "we're green, buy our stuff" commercials). For personal commuting to work? Your commute needs to be at least 37.5 miles for driving 75mph to save you 10 minutes over driving 55mph. Is 10 minutes worth a Middle Eastern oil dependence? Do you really want to get to work faster?
... perhaps the gov't ought to outlaw off-road vehicles, like jeeps, with their non-aerodynamic light bars and canoes. =)
I realize, of course, this was said in good humor but it's a statement that many have made before. For a white collar world, such a measure isn't entirely off base. But America does make good use of its pick-up trucks and specialty vehicles, a role not well filled by a Prius, Yarus or equally-ugly-&-small-us. As far as SUV's go ... almost none of them serve any purpose that could not be equally served by a mini-van. An off-road 4x4 [Land Rover / Jeep Wrangler] do differentiate themselves from SUVs (ironically, the New Jersey DMV lists my Wrangler as a station wagon) in their ability to actually negotiate rough terrain. All of this is only relevant when one actually uses their vehicle for such a purpose. Mine has served well in driving me into the wilderness for mountain biking trail heads, remote campgrounds and fording through seriously bad weather whilst other vehicles slog along at 20mph or get stuck. For the record, I use public transportation (buses and subways) for my day-to-day commuting and the Jeep for my recreation.
RE: legislation is not always the answer by Anonymous :: NR0 :: on 09 May 2007
i wasn't saying that driving faster saves gas, just that forcing people to drive slower probably is not going to help.
not having read your article on mileage that you cite, i wouldn't put too much faith in the derived stats. keep in mind that your jeep was not designed to go fast on the highway, compared to a BMW.
and i don't want to get to work faster, i want to get home faster. =)
RE: legislation is not always the answer by VnutZ :: NR8 :: on 09 May 2007
not having read your article on mileage that you cite, i wouldn't put too much faith in the derived stats. keep in mind that your jeep was not designed to go fast on the highway, compared to a BMW.
Those stats are about as accurate as it gets short of having a professional dynometer - they were sampled straight from the engine computer by tying a laptop directly to the OBDII port. Using the Jeep helped to demonstrate the extreme owing to its drag coefficient.
Now like you said, a BMW is designed to go fast, as are other sports cars. That does not, however, equate to being designed to be fuel efficient. The ability to go fast means having the horsepower to push through ever increasing pressure (from the article) of built up air. This is why the Bugati Veryon (sp?) is supposed to be awesome with its 1000hp engine. The quest for speed is answered with lower coefficients of drag and ever increasing amounts of horsepower.
The pursuit of such design improvements are handy - technology to make a vehicle safe at high speed will trickle down to make low speed vehicles safer. So I don't disagree with the need to continue the pursuit of engineering performance vehicles. On the flip side ... there is even less use for owning a vehicle that goes ridiculous fast than there is for a vehicle that can haul a load or navigate off-road. :-)
I only bring this alternative up because Americans complain they want to reduce the stranglehold held on us from oil. But when an immediate remedy is at hand, that requires a little self control ... we don't want to have anything to do with it.
RE: legislation is not always the answer by Anonymous :: NR0 :: on 10 May 2007
and i'm saying it won't work for a variety of reasons. anyway, if you want to make an immediate economic incentive to force people to drive slower (assuming the slight drop in speed is really worth it), don't use speed limits - put a tax on gas and tell everyone to conserve more. tax gas at ten cents per gallon or something, and have that tax go directly to government-sponsored energy research. that way, the future tech is also not in the hands of oil companies (who profit from maintaining the status quo).
also, as high as the gas prices are, you know the oil companies are making a shitload - even the US ones. was it texaco or someone that reported ridiculous gains a few quarters ago? actually - chevron was one of them yahoo article. note that this is the same thing that happened in 1973, during the "shortage." Time article from 1974
55mph vs. Gas Tax by VnutZ :: NR8 :: on 10 May 2007
and i'm saying it won't work for a variety of reasons. anyway, if you want to make an immediate economic incentive to force people to drive slower (assuming the slight drop in speed is really worth it), don't use speed limits - put a tax on gas and tell everyone to conserve more.
I think we're looking at this slightly differently. Lowering the national speed limit would dramatically save gas, if it were followed. To your point, it won't work because people won't obey it. I agree with this. Even with posted speed limits of 65 and 75 people in non-aerodynamic cars are still racing at 90.
I don't think a gas tax would make a real difference. People are going to pay the price of gas regardless of what it is. After all - you need to get to work. The old "Sorry boss, I can't afford to come to work today," excuse won't last too long! Even if gas were taxed at a dollar a gallon, America would still have cheaper gas than many other places in the world. Good for our government's budget though!
You're right though, people won't slow down or cut back on usage until it really hits the wallet. What hits a wallet? Traffic fines. Speeding tickets. So boost the state troopers budget and have them enforce a lower speed limit. That creates jobs. Their efforts put money back into the state. The effect of their efforts reduces oil consumption. Reduced oil consumption lowers demand from the Middle East. Lower demand drops the price of oil.
This works great until China and India say, "fuck it all" and just burn up the surplus we've saved.
also, as high as the gas prices are, you know the oil companies are making a shitload - even the US ones.
True - but so what? They aren't in the oil business to be altruistic, they're in it for money. To put it into perspective, would you still work for your company if you were told that due to national interest, your services were being socialized and turned into a non-profit organization ... here's your paycut? So it's not really fair that consumers lambast the oil companies for turning a profit at rising prices. That's a sign that capitalism is alive and working.
It would be wise to pump your investment money into energy companies. Why? Because they are turning huge profits. And they know when their supply will exhaust and will be at the forefront of alternative sources ... energy investment is win-win for everyone. Let their "conspiracy dollars" become your dollars. Heck, when you buy gas, you're funding your own investment! They've made my investment portfolio fatten.