Gas Mileage of Automobiles

One needs to allow for the difference in size between the US Gallon and the Imperial Gallon, of course, which is something a UK citizen may not allude to, out of mischief.

"Size is important".

(Especially in keeping wallpaper attached to the walls......)

We were traveling between Austria and Italy, through the Alps, and I managed to get a photo of the buses speedometer... which was about 100 km/hr.

Back in the US, we did a slide show, and I slipped this photo in while discussing our "casual" trip through the Alps. Now of course, Americans will think "Autobahn", and some will remember an Alpine trip from the movie "Goldfinger" with switchbacks and heavy elevation changes between each switchback...

I didn't have the heart to tell them that this was on modern freeway, and it translated to about 60 miles per hour.

Bill

I cannot answer the question why us industry did not increase mileage but I can only say that some European compact cars reach > 75 mi/gal. May be one reason was the gasoline price in Europe a lot higher than in the us and this before the question of environment became a daily question. 1L super costs >1.4 Euro = $2.21 1 gal= 3.785 L.

With such prices it was compulsory to increase mileage as soon ans as much as possible.

Hi Guest

This subject has often been discussed in various forums at length, and almost all of these discussions never brought out any Engineering Solutions to the "original" problem: Creating better efficiency of Energy Transfer by fuel burning inside the IC engine.

One such discussion thread initiated by this writer is:

http://cr4.globalspec.com/thread/14678#newcomments

Your question: "Are we using more gasoline to drive a given distance and generating more total pollutants than we would be if we had more efficient use of the engines without the pollution controls and used less gasoline?" ... requires Engineering to improve the energy transmission efficiency. We need to redesign CARS not as mere show-piece mega luxury systems but as environmentally appropriate transportation systems for private persons, without excessive CO2 and GHG emissions (apart from many other pollutants being emitted) per unit of travel. This would also call for very serious interactions and discussions amongst a number of stakeholder groups, so that quantifiable yardsticks are defined and systematized, and finally ENFORCED.

It is hoped that if not the auto manufacturers, the public at large come to recognize the seriousness of this gigantic problem, well before it reaches ominous proportions that nothing could be done at all ... resulting into unprecedented catastrophe'

pvhramani

I read the posted thread and applaud the efforts and thoughts put forward. It seems that weight reduction is the major issue (materials of construction). As to strength of the vehicle body for safety issues, that can also be adressed by materials of construction and "requirements" on automotive design.

But, what about the observation that the European vehicles use so much less gasoline for a similar weight vehicle, as I observed in another post. Shouldn't carmakers be held accountable for the total emissions from the vehicles.

It should be noted that the problem of gasoline burning in IC engines, finally providing hardly 12% of the heat output into mechanical energy to push the car, needs to looked into more holistically. Thus, the original question of "gas mileage" cannot be looked upon in isolation but needs to be considered paralleling certain socio-economic aspects, about which some fact are presented below:

The world population is about 6.6 billion. Over 3 billion amongst these are not earning $1 per day; 15% of the world population, living mostly in the developed world, consume over 80% of all food, resources and energy in the world; the US alone accounts for 30% of world pollution due mainly to automobiles and aircrafts. A few countries have absolute disregard for the majority and go about "gulping" energy and inflicting (if not dictating) their own brand of socio-economic paradigm (i.e, one for themselves and another for the others) on the majority, by shear brute force. But, history is replete with enough examples of "fallen" Caesars and Hitlers that, if the writing on the wall is NOT read and understood, the "thermodynamic" diktat of Entropy (and heat death of the universe) would soon catch up. But all these could be delayed and human race could live for more millenniums without fear of self destruction.

We engineers cannot simply look at all these as effects of mere "consumer dictated' and "market driven" phenomena, and be totally oblivious like the Ostrich with its head pushed into the sand. The prophetic expressions of Prof Galbraith (1964) in his "Affluent Society" seem to becoming realities now.

Thus, it is imperative that in a world where artificial boundaries cannot simply shut different cultures, any technological matter would have to take into account the impacts not merely on the local surroundings, but would have to be holistically designed to be benign to the world at large.

The case of the "Gas Mileage" is just one such situation; but of very great importance!

So you are comparing the US to Rome or Nazi Germany? In what way has the US inflicted or dictated our brand of socio-economic paradigm on you? In what way have we used "brute force" against India? I think that the vast majority of people in your country are trying very hard to have a life equivalent to that in the US, and through no fault of the US.. Feel free to return to your grass shack in the bush if you wish. I for one certainly will not force my brand of socio-ecomomic paradigm on you.

With 50% of new car sales today being SUVs and pickups I suspect the buying public is simply saying that they really don't care.

As prices rise I think you will see more interest in better economy, but it will be slow to change. Auto sales are down, so nothing is going to happen too fast.

All imported cars must meet the same federal emission standards as domestic cars.

Domestic auto makers seem to focus on the larger and heaver market whereas import manufactures have had the small and light niche market. Even that has been changing and cars and trucks from Toyota, Mazda, Honda, and others have grown quite noticeably in both weight and size.

Another factor is that the USA is huge and we tend to drive longer and further than many people in other countries.

Finally, the posted fuel economy of cars does not match the actual observed mileage you get. It depends on the manufacture, but some EPA estimates are a bit inflated compared to what the real driver gets. Others seem to underestimate the mileage.

My import is grossly underrated. My car states something like 22 mpg highway. I did a run at 67 mph with the cruise control on and averaged 31.8 mpg highway after a two hour drive. Not too shabby for a 3.6 liter, 400 hp car!

Auto sales are down

The signs may have a different meaning.

The pump prices here have resulted in people deciding that owning a car is becoming a burden instead of a convenience. Several people I know have now gone to taking public transport rather than use their cars. Some have even sold them. Even more are thinking of holding off on buying a car just because of the price of fuel. Hence, car sales may go down because of the fuel prices.

It would be in the interest of car manufacturers to build very efficient cars since this makes owning a car much more bearable. People are beginning to look at cost-to-own rather just the cost-to-buy. If they come out with fuel efficient cars, I think car sales will increase.

As long as it doesn't cost an arm and a leg (or more).

I would like to be able to utilize public transportation, but I also wouldnt like the necessity of living in the congestion of a city. Where I live, public transportation while available is expensive and quite hard to get to in order to ride (ie: routing issues). Perhaps if gasoline costs increase enough, more people will ride the buses and the routing will be improved for the public.

The use of automobiles in the US has grown over the decades because of good roads (I wont say good maintenance), but at the expense of trains and public transportation. That is too bad, because when I am in Europe or Japan, I find riding the trains and PT very convenient and cost effective.

I'm with you Doc, if I could ride the train to work I certainly would..

Dear Anon--Hero, Your Last paragraph could have been desribing a two hr. drive in my 4dr Regal Buick. Two slight exceptions: I've 3800/3.8 v6 & and achieved 38 miles per Gallon. If my Canadian Gallon, is being compared to your (possible Americian Gallon) the extra Quart in our gallon, -- this would be close to same.

I noted: no one mentions how well the Engines Average RPM to vehicle weight, and how well this is matched in Diferential Ratio at the variuos Gears. This has made a lot more sense to me than the size of the vehicle, burdened with a Power Hungry Gas Guzzler.

Keep trying !!! I,m only 70 & enjoying, soon to pass 2,000,000 miles, in everything from My Dad's 10 ton Cabover Highway Tractor, to my 1956 MGA Convertible & only owned 108 personnel vehicles, since 1 was 15 yrs. old. Your Hi-way Friend, Carl.

Go check out the diesel models from Volkswagen. Diesel is pricey now, but the mpg is much better.

And I suspect that the increase if fuel economy of the diesels is one reason why the price has risen to be much in excess of the price for regular gasoline (even beyond high test). Remember a few years ago when the gas mileage with diesels was poor, the price of diesel fuel significantly trailed that of regular. It is interesting, given that diesel fuel is low grade fuel compared to the octane levels of normal gasoline fuels.

Actually the price increase in diesel in the US is related to the upgrade to ULSD, ultra low sulpher diesel. Getting the refineries converted and getting the production levels up has raised the price.

The other aspect of diesel prices is related to the season. In the late summer and into the fall the refineries optimize toward fuel oil. This reduces the diesel stock. In the late spring the refineries shift back toward diesel. The price of diesel should come down over the summer.

The fuel consumption of European petrol/gas cars has remained static or even deteriorated over 20-30years for reasons already duscissed here mainly due to weight (safety and comfort demands), emmissions (stoichiometric requirements for exhaust catalysts) and performance. Diesels have on the other hand improved dramatically with improved fuelling and a pile of research and developement. Dammit you can not only live with them but almost enjoy driving them!

We have to at some stage face up to the fact that our habits have really got to change if we are to sustain either the mean standard of living and/or the levels of world population we have currently. Never mind arguments about CO2 and climate change, there simply aren't the resources to make it sustainable.

I think it is unwise to think or expect any governmental policies to truly effect change, because the 'sale' of ideas is just another form of marketing, and as the issues change, by premeditated choice (don't get me started here) or otherwise, that which WAS 'important' is no longer.

The auto companies, also being good marketers (as anyone who tries to sell their products should be), also 'sell' what is important. When we (USA) were all sitting in lines waiting to hopefully get gasoline for our cars, fuel economy was at the forefront of our thinking, so whether driven by government or by brands, getting more MPG was important to us. BUT, we all have such short attention spans .

Although I'm not quite ready begin all my sentences with, "when I was your age", I can remember when gasoline in the States was about US$ 0.35 per gallon. We all saw the increases, especially during this or that publicised 'crisis'. But I was always amazed that when the prices jumped from, let's say US$ 1.50 to US$ 2.50 per gallon, everyone gasped, but all were immediately relieved when it dropped to US$ 2.00 per gallon. Its as if, even in that very short period of time, everyone forgot that it used to be 50 cents cheaper!!!

During those 'crisis' periods, there was a flurry of activity aimed at making the autos lighter in weight, and more efficient. One new and growing industry focused on active suspensions, and active noise-cancellation to replace passive systems. During those 'crisis' moments, those upstart businesses seemed to be flourishing. But, suddenly, as the whole 'oil crisis thing' seemed to pail against other more interesting news issues, the demand for those improvements suddenly ceased.

[SIDE BAR: I remember once standing in line to pay for my gasoline purchase, hearing the lady behind the counter, tell each person in turn, "you better fill up today, 'cause tomorrow the price is gonna go up". When it was my turn, I asked her what she drives. She pointed to a huge SUV in the lot. I asked her (several questions actually) about how she used it. "I just drive it 20 miles back and forth to work". If we don't care, we really can't expect others to care of our behalf.]

Without knowing the science of engines and fuel and power-to-weight ratios, I can only speculate that there are many possible improvements that could be made ... if only it were important enough to the masses to demand it.

Sadly, whether we are talking about the logic versus action of the eco-system, the economic situation, or gas mileage, nothing, beyond the gentle trickle of 'improvements' stating 'ours are better than theirs', will happen until the general population demands it.

Demand and supply is the only thing that makes things change.

yes engines are more efficient these days so a smaller capacity can produce more power, but power output is completely dependent on fuel consumption. So smaller cars are more powerful, everyone goes faster, accelerates harder and burns more fuel. If acceleration were limited and cars designed for legal speed limits (In the old days not many cars were capable of 100mph) and were lighter, cars would be more economical. However their drivers would be bullied by scornful arrogant drivers in more powerful cars. Purchasers relate power output as being representative of their manhood size, and weight and size equate to safety so no one's going to buy without additional incentive.

That is a very good question, also forgien automobile manafactuers produce 6 cylinder engines that have the same or more horsepower. All auto entering into the US are required to meet the same pollution standards as those produced in the USA.

Don't throw around numbers, the European cars are not that economical, if one sets aside the exceptions. The Diesel-"Smart" and the Gasoline-Hybrid-"Prius" can barely make it to 60 mpg. Change the "Prius" super low rolling rezistance tires with more drivable ones and the 60 mpg becomes a mith. And the purchase price is not offset by the fuel economy. And the price reflects the economical input = industrial energy consumption. When did you walk last time to the neighborhood store ?

I own a 1993 ford festiva. I get, on average, city/hway combined, approximately 37 MPG. Not accelerating as fast as I can, but not poking around either. !993 was also the last year that the festiva was produced, problems with incorporating airbags was the reason. Yet the same model is STILL produced around the world! I have close to 600,000 miles on mine. A very good, gas efficient car, with a high level of reliability. Pay no mind to detractors who say small cars have a problem on the hway, mine does not feel a trucker passing by. Talk to actual owners, see www.fordfestiva.com.

Yet, today, not even the Prius I drove for 3 weeks approached the same gas mileage, if driven about the same(full throttle all the time to get comparable acceleration). Why can not car manufacturers make a gas miser like this now?

Answer: same as what has already been stated, not enough people in the US care, but also, it seems to me there are more reasons.

Why is it that if I, a US citizen, go to Canada to buy a smart car, I must pay an additional $5,000? I have yet to have an answer to this one, but it must be something along the line that our government claims to want to be more energy efficient, but does not really mean it. Why else inflate the price of a gas miser like the smart car? I would buy one in a heartbeat for 6k, but 11k? Not a chance....

The Model T Ford got about 25 mpg with its primitive 4 cylinder engine. Gee, so much progress we've made.

I think a plug-in EV with a 50 mile range, using a small steam engine to run a generator to go farther would work very well. Mpg would be good since about 80% of driving would be on electric power and only the rest would use fuel. External combustion is cleaner and can use more kinds of fuels. Using a condenser, a Lamont boiler and a Cyclone, Green, Lysholm expander or Tesla Turbine as the engine to get rotary power, plus insulation, modern alloys, computerized controls and such it would be even more efficient than the Internal Combustion powered car.

beesidemeusa@yahoo.uk.co - has a lot of info on this concept.

To All, The reason car manufacturers haven't improved the gas mileage to keep pace with the technology (fuel injection instead of carburetors, digital computer control instead of analog feedback) boils down to one thing: money. It's not in the best interests of those who own the car companies to disenfranchise those who fund them: the oil companies.

Why are mileage ratings better in Europe? Because Americans were willing to consume more fuel until the prices went through the roof. And because other countries didn't need as many cars because of good public transportation.

If you think the oil companies don't control the car companies, research who funds most "new car design" studies.

I worked in the auto industry (design) for twenty two years, I have seen some of the most incredible crap passed off as "the next big thing."

The other problem is that the ICE is a very inefficient engine, BY DESIGN. Most of the fuel, (at least 70%) is used as a supplemental lubricant. Also the engine temperature is kept artificially low because of metallurgical restrictions.

You want better mileage? Get the oil companies out of the picture. Find alternative fuels. I have, and no, I am not elaborating on that. Do your own research.

My two cents, Blue

A well designed steam engine is much more efficient than internal combustion. Even more so if used in an electric vehicle to generate electricity to keep the batteries charged when driving beyond the all-electric range. A steam electric hybrid would save a lot of fuel, be lower in emissions, have more torque, start instantly and could be made to use any liquid or gaseous fuel.

Europeans demanded better mileage and the tests were different.

A steam-electric hybrid could drive a large, feature-laden car and use much less fuel as the first 50 miles would be driven as a plug-in EV [about 80% of the time] and the steam-engine would power a generator to keep the batteries charged as needed. A condensing, hermetically sealed, insulated steam engine is more efficient and less polluting. Look up Doble steam cars. Also Lamont boilers, plus Cyclone engines, Green Steam engine, Lysholm expander and Tesla Turbine as possible designs providing rotary power.

I agree, it would be great to see some of these technologies developed.

This comment about the "power" of cars today is right on the money in my opinion. I've been watching the power of cars go up and up over the years and been asking "WHY?"

One of the most popular cars in history was the VW Beetle. I believe it started at around 30 HP. It was no race car but it did the job. Geo Metro 55 HP.

So why does the new Honda Civic need 140 HP SOHC and 197 HP DOHC !?!?!

The Civic gets great fuel economy. But I imagine it would get even better if it was tuned and designed to focus on economy and only have 90 HP.

Trucks are the worst. Military trucks have had 4cyl gas engines. Strategically they needed to be fuel efficient. Moving large amounts of fuel to supply them just didn't make sense. They did the job through all of the worst conditions. So why does Joe-Blow need to drive a 10 cyl diesel to work every day?

In north America it seems we would all be driving rocket cars next year if we had our way of it.

One of the most popular cars in history was the VW Beetle. I believe it started at around 30 HP. It was no race car but it did the job.

And people loved their Beetles. I think no other car had so many people so enthusiastic. The first Honda Accord might be in second place and as a result, sold for over retail to most buyers. The Prius has a somewhat similar cult following. I think it is foolish of Toyota to dilute that brand quality with all the overpowered hybrids they've since brought out. The hybrid Camry is the exception, but otherwise, the newer hybrids have been brought out to deliver high performance without reducing fuel efficiency too much.

I'd be just as embarrassed to drive a Suburban as I would to live in a McMansion, but for most people, it appears that there is a tremendous draw to consume as conspicuously as possible. To me, Hummers shout, in the loudest possible way: "I have insecurity issues and have bought this thing to compensate." Viagra would be so much cheaper.

"If the American and European cars are the same size (weight) and engine, why are the US versions so much less efficient?"

Are the US ones less efficient or is the method of measuring the mpg different? I know that the European tests are for a standard driving cycle intended to give an average across a range of driving conditions. How is the US figure obtained?

You said: "Even in these days where the use of highly tuned, computer-controlled electronic ignition fired cars with electronic overdrive, gasoline mileage still only hovers at ~30 miles/gallon (mpg) - highway for most small cars and is less for larger cars."

Probably true for "most" small cars. However, if you look you can probably find some that get 40 mpg or very close to it. You can get 50 mpg if you want to spend money for a hybrid. Honda did make the Insight for awhile that got 70 but they quit making it. If money is no object I'd go Hybrid: either Civic or Prius.

You can buy a scooter that will get 70 or more I think.

I think the Honda Fit and the Toyota Corolla get close to 40 mpg, maybe the Toyota Matrix and others also. The Civic will get close to 40 mpg, and they are very nice but too pricy now days. If money is a concern, I would recommend buying a used Honda or Toyota, about 5-6 years old for and save some money. Buy a 100% original equipment car, from a non-smoking, one-owner, without any fancy wheels, loud exhausts, spoilers or other garbage that idiots like on their cars. Get a car with 30-60,000 miles on it. Before forking over the money, take it to a dealer and pay $50-$150 to have them do a thorough checkup on the car, including a VIN check to see if it's been wrecked. A Honda, if it has been taken care of will easily go 200-300,000 miles and you'll save some cash over a new one. Probably similar for Toyota. For better mileage, get a strippy model: manual roll-up windows, manual transmission, no air conditioning, etc. Those cars are not luxurious, may be hard to find, but are economical. If you want more luxury buy a new one or get one with air conditioning, etc. The new Civics are very nice, will get near 40 mpg if you drive reasonably, maybe more. I personally don't like the fact that the engine is stuck up under the dash on the new Civics but if you aren't a mechanic it may be OK. I'll check out Toyotas next time just because of the engine being stuck up under the dashboard on the Hondas, but I am partial to Hondas. Pray for $10 per gallon gas to get the monster SUV's and pickups (all driven by retarded morons) off the roads so you'll be safer.

I do hear that VW makes some 50 mpg diesels. Don't know how reliable they are. Eventually they'll stink like all diesels do.

My experience with the small cars is that they will exceed the EPA mpg rating on the highway, except in winter when the fuel is oxygenated, then mpg drops 10% or more. Ethanol may also have a negative impact on gas mileage. Ethanol is being forced on us even though it is a stupid idea.

To answer your question on why US cars get such poor mileage today: Americans, the majority of which have no sense of personal responsibility, or responsibility to their nation or planet, are choosing more powerful vehicles over more sensible vehicles that are less powerful and that get better gas mileage. The government being made up largely of inept idiots has allowed the car companies to produce gas guzzlers with absolutely no control whatsoever. To summarize the cause for the poor fuel efficiency of automobiles sold in the United States today: You live in a nation of GD irresponsible morons that have no government controls, no personal common sense, no integrity, and who intentionally waste the fuel that grows our food, runs the military that defends us and that runs the world economy. Welcome to America.

Great answer!

Ethanol may also have a negative impact on gas mileage.

You're right. The flex fuel Tahoe in-town mileage drops from about 15 (awful) on gasoline to 11 (obscene) on E85!

Here's a quote from a Car and Driver article:

• For example, a four-wheel-drive Chevrolet Tahoe 1500 with a 5.3 V-8 and automatic has an EPA rating of 15 mpg city and 21 mpg highway on gasoline but only 11 and 15 on E85. This info is not on the window sticker; indeed, we could not find it through any GM sources.

I do hear that VW makes some 50 mpg diesels. Don't know how reliable they are.

The engines are very reliable. The rest of the car is like any modern Volkswagon -- OK, but not up to the standards of a Honda or Toyota.

To answer your question on why US cars get such poor mileage today: Americans, the majority of which have no sense of personal responsibility, or responsibility to their nation or planet, are choosing more powerful vehicles over more sensible vehicles that are less powerful and that get better gas mileage.

Wouldn't it be nice if we could say that you are overstating the case, or that we Americans really think about our personal responsibility. Wouldn't it be nice. Unfortunately, the vehicle buying statistics bear out your contention precisely. Our behavior (not what we dream our behaviour might be, but our real behavior) says we don't give a hoot about saving energy. And the phenomena is not limited to automobiles. In my county, a very large percentage of the homes (about 50% of the homes built here in the last 3 years) are at least twice the size of the home I grew up in -- which was, itself, pretty lavish for its day (1960's) even by American standards and at least twice the size of a typically upper middle class European home. Whatever happened to placing a value on modesty, compassion, responsibility, integrity, sharing, and a sense of leaving something for the rest of the world? Here, the guy who dies with the biggest box of toys wins.

(A typical rationale for an SUV: "I have to own one so I can tow my boat." And how does the boat perform? 2-6 mpg, with emissions, for the cleanest new boats, of 10 times those of cars. 2000-vintage two strokes can put a gallon of gas directly into the water unburned for every 8 miles travelled -- let alone the four gallons burned in 8 miles. You used the term "morons." Can anyone argue that pouring raw gas into our lakes at the rate of about 1 gallon every 12 minutes -- for a boat cruising at 40 mph -- is anything less than moronic.)

90% percent of the time, 90% of Americans could use cars selected on the basis you described, and by so doing we'd cut our oil usage by 40%. By so doing, we could be largely free of death grip imported oil concerns have over us. (We'd still require imported oil, but we'd have more options, and some market leverage.) Instead, to avoid having to drive the sorts of reasonable cars that most people of the world would be thrilled to own, we send our kids to die in Iraq to secure our oil interests in the middle east, so we can drive land yachts. (Perish the thought that we would have any concern for the 600,000 Iraqis killed, or the fact that we now have created a haven for terrorism in Iraq -- these are concepts far too abstract for the average American. But couldn't we at least hope that American's would not send their own kids to their deaths to avoid having to drive anything less than a palace on wheels?)

Any Tahoe driver is doing far more than his fair share to directly fund terrorism. Without the oil money we've paid to Saudi Arabia (Bin Ladin's country, and the country of origin for virtually every terrorist involved in 911) Bin Ladin would be out of business. Whatever happened to patriotism?