Why Do Cars Use So Much Fuel?

I think that weight is the big issue. All the additional safety gadgetry has added a lot. Add in the need to survive an SUV crash, and you can see how this might be a problem. Look at the new mini, it weighs double what the old one did.

I also think it has a lot to do with the public not understanding (historically) that to use less gasoline is a good thing...but the fact that we are heading towards "peak oil," in the paraphrased words of oil tycoon T Boone Pickens (from the Playboy Interview):

"It doesn't matter if we have fuel efficiency now...when we run out of the stuff, we'll be FORCED to find an alternative. And biofuels aren't the solution if they continue to use petrol as the main ingredient. People don't understand that the real crisis will come when there is NO MORE PETROL in the world."

And compared to other parts of the world, petroleum products are still relatively cheap in the USA. I drive an unleaded-gasoline 4-door sedan, and heat my apartment with natural gas. If I had more windows on the southern-facing side of my apartment, or new windows, I could get away with not heating the place at all in winter!

If the American car companies don't jump on the increased MPG bandwagon soon though, they'll go bankrupt. Toyota has already bypassed GM for the first time in sales. Why is that? Consumers want to spend less on gasoline, so they try to get the most bang for their buck. Sacrifice a little style for economy? That's ok, as long as money is saved in the future.

How about smaller engines? Instead of fighting over how much HP the machine can put out, make one that has less HP but more fuel efficency.

There were / are cars that can achieve amazing fuel economy, VW had the Lupo which was a sub compact car that used 3L on 100km of driving (average), the downside was: It wasn't big and impressive.

This is not only an engineering problem, this is also a preception problem, and the car industry, especially in the US, for a long time has touted "Bigger is better" and "The more HP the better".

So, even if GM or Ford would put a car out tomorrow that is ultra fuel efficent, it would fail on the market because it most likely won't have the look that is expected by many.

It comes down to weight. If you look at a graph of the weight and fuel economy of cars over time, you'll see that relationship clearly. Especially after the oil crisis, you see the fuel economy gain drastically as all the additional weight was cut on cars.

So automakers went to lighter materials, but realized they weren't as safe. So they started making them bigger and with a lot more safety gadgets (airbags, for one) and so, the weight was put back on and then some.

As for the ideas above, can you really picture people picking cars for their aerodynamic features, and not their aesthetics? Those are the people who are buying the Prius. But even a majority of those buyers won't put up with computer controlled acceleration rates.

Every time I hear people touting new technologies for saving gasoline I laugh. In 2002 I bought a brand new Saturn SC-1 with a manual transmission. The lightweight car, sub 2400 pounds, and small engine, 100 bhp, produces results around 41 miles per gallon on the highway where I do most of my driving in rural Iowa. This is a car with air conditioning, CD, power windows, etc. BTW, it cost under $15K when all was said and done.

What is funny is that there is very little sophistication in that car. The engine is a SOHC without variable valve timing. The body is lightweight plastic, but it was something that Saturn had been doing for years prior. Sure, the shape of the car is very aerodynamic, but that is not a feature unique to that specific car.

It is ridiculous that new cars are "having trouble" achieving higher mileage when less technologically proficient predecessors could do so.

I think you better check Toyota's sales, I'm certain they are not all high MPG cars. Many trucks and SUV's are up there.

"car heaters" as something sapping fuel economy? Thats WASTE heat. If anything, you are improving overall energy efficiency.

And think of all the miles driven when you get lost without the GPS. I doubt that sucks more than 1/2mpg. So, on a 200 mile trip in a 34.5mpg car you would use 5.714... gallons of gas. On a 210 mile trip (you make a wrong turn) in a 35 mpg car, you use 6 gallons. Thats 3/10s of a gallon MORE.

Can't you authors THINK before posting. Its not the GPS or heater thats killing fuel economy, its the extra steel they put in to keep you safe.

And anyone getting less than 50mpg in a prius needs to get their car looked at.

The name of the game is horsepower to weight ratio. Not just weight. Not just HP. Every freshman engineering student learns its all down to the HP/weight ratio.

Haven't seen the plot for how these compare in today's models compared to decade of the 80's when mileage and safety standards of today were set, but I'm willing to wager that the HP/Wt ratios have almost doubled.

With the exception of tradesmen and trailer pullers, all that power is only about one thing: satisfying the human ego of men and women. People with zero personal power in their lives can get the 480HP engine and feel like they're really something. All those arguments about getting into traffic with power are a self deception .

Sigh...this was such a great post, with so much insight and great suggestions.

How unfortunate that yet again, it happens to be littered with the desire to make other people drive slow...as if that's going to solve all the emissions problems that the world suffers from.

Accelerating fast is necessary. Can you imagine braking hard to avoid hitting road debris or another car that has stopped without warning in front of you on the highway, and not being able to accelerate quickly to get out of the way because your car is governed?

How will cars be able to change lanes safely on the highway if they can't accelerate past a certain limit? Have you ever driven in the mountains (I live in Denver, CO, and believe me, your car doesn't do the same on some of our passes as it does in the city. A four-cylinder car becomes a mule) and seen how a car performs at altitude?

Have you taken into account that if everyone drives slowly, it leads to heavy traffic congestion, bumper-to-bumper traffic, and loads of cars idling, causing lots more damage than if traffic were moving at a reasonable and steady pace?

Take these things into consideration before subscribing to the "if everyone were to drive slow, it would solve almost all of our problems" mentality

toyota is providing what the customer wants. be trucks and green cars. they are on the money.

on another note. the enzo doesnt have cd player or warmed seats and all that tripe. so thust it has awesome MPG ... hmmm .. might not be a good example.

ppl will NOT compromise for a something they need when they can buy something they want.

fuel efficient with all the comforts and safe is what they want. its what i want. tho i love my small medium size car, easy to park but can seat everyone and move my house.

Listen to the stereo if you’re bored, and read a map if you’re lost.

A GPS unit gives you the confidence to "get lost." And by getting lost you find out of the way things that you don't find if you stick with interstates.

It also gives you the ability to get off of the highway when you run into a traffic jam and keep moving rather than sitting burning gas.

And a GPS unit can run on one or two watts of energy. The one my wife and I have uses two AA batteries and runs long enough to get us through a whole week of vacation.

The biggest losses aren't gadgets. It's transmission losses and efficiencies in the engine. Use less powerful engines in lighter cars with CVT or manual transmissions and you'll see fuel economy go up.

That 80's Ford Fiesta, which you seem to have a teary-eyed nostalgia for, also cranked out probably on the order of 95% more polution per mile than a modern vehicle. Not to mention the fact that it would never pass crash safety test nowadays. That thing would fold like a pop can.

Your wish list of miserabalist non-features happens to almost perfectly describe an East German Trabant. Now all you need is a centrally controlled economy and a police state, and people will again eagerly put their names on the waiting list. Until then, no thanks.

Transmissions are a big power loser.Specifically automatics transmission.Manual transmission have a direct connection to the engine.Which means no power loss.

Transfer cases are also power loser.Chain drive transfer cases like the np231 in jeep.Chains stretch.With an atlas/np205 or dana 300.There is a constant gear to gear contact.

Open differential's lose power.They tend to spin the tires with zero traction.But most run with them for noise reasons.Some limited slips and lockers have bad habits-noises.

First of all I have to call BS on a Fiesta comfortably seating 5 adults. That back seat was a joke and I had a dodge colt around the same time and that isn't exactly a limo.

Second the reason the overal mpg hasn't changed over the years is that fuel economy hasn't been the priority. Safety has been and still is. That's why people have been buying bigger cars and the weight has increased due to added steel and various safety devices.

Cut the Gadgets – Cars are methods of transport; they don’t need DVD players, electrically heated seats, GPS systems. Listen to the stereo if you’re bored, and read a map if you’re lost.

Lets take a look at this

DVD players - I don't really want a DVD player in my car, and I am not really sure they are that useful, even for keeping kids entertained. However, a motor, a laser, a chip and a small LCD screen do not use that much electricity.

heated seats - this is probably the worst energy hog listed here and one that might be worth getting rid of.

GPS system - a chip and a small LCD. This does not use a lot of energy.

None of those things weighs that much.

Compared to a smaller body, a lighter body, a more aerodynamic body , and a smaller engine, the gadgets are not going to have a big effect. And while we do need more efficient gas cars, we do not need to squeeze out every bit of efficiency as much as we need to switch to electric cars.

Point taken about the efficiency of the Ford Fiesta. Little cars rock!

But it seated 5 comfortably? Only if your family was made up of midgets!

I agree with pretty much everything that's been said here. A standard, belt driven alternator uses energy pretty much all the time, and the amount of draw from a GPS, stereo, windows, etc doesn't increase this load appreciably. The weight of these gadgets probably has more impact on economy than the power they draw.

The number one factor for increasing mileage is weight, with a close second being the driver. Honda CRV's got 45mpg back in the 80's because they were light and "under" powered, not because of some miracle technology.

Regenerative braking is not the answer either, unless you've got something to do with all that energy you're generating. Much better to time taking your foot off the gas and coasting to the stop. I wouldn't mind seeing the same kind of engine off/on control that hybrids use on an ICE only car.

Just for fun of it, I have entered several variables into a Prius Energy Use Simulator to show just where each part of the energy is being used at several different speeds.

This simulation is based upon the following variables:

Temperature: 88F
Wind: 5 MPH
Wind Dir Relative to Vehicle: 90 degree crosswind
Barometer: 30.03 inHg
Rel Humidity: 68%
Elevation: 410 ft above sea level
AutoAC: ON
Climate Cntrl Setting: 75F
Fuel: 114,500 BTU/Gal-US RFG (Reformulated Gasoline - typical pump gas)
Tire Rolling Resistance: 0.0077 (OEM tires @ 38/36 psi front/rear)
Road Rolling Resistance: 0.001144 (smooth dry asphalt)
Cd: 0.26 Cd (Coefficient of Drag)
FA: 2.16 m^2 (Frontal Area)
cwCd: 0.000014 (Crosswind Cd Correction)
cwFA: 0.000085 (Crosswind FA Correction)

MPH...AeroDrag.....MechDrag.......TRR............RRR.......AC+Misc.....Aero%
40.........2.09kW......1.66kW..........1.92kW.......0.29kW....1.04kW......29.8%
50.........4.09kW......2.98kW..........2.40kW.......0.36kW....0.99kW......37.8%
60.........7.06kW......3.18kW..........2.88kW.......0.43kW....1.02kW......48.4%
70.......11.22kW......3.62kW..........3.37kW......0.50kW....1.03kW.......56.9%
80.......16.75kW......3.72kW..........3.85kW......0.57kW....1.04kW.......64.6%

For those interested, the MPG for each of above would be:

MPH.....MPG
40.........74.22
50.........60.13
60.........53.51
70.........46.13
80.........40.12

Best Regards,

I drive a '95 volvo 850 station wagon, which until recently was loaded with everything I wanted with me for the three or four months on the road visiting people and camping in or out (I wouldn't say that it was light). I almost always have the stereo going (loud) when I drive, and cannot turn the headlights off without leaving the parking lights on even when the key is out (I always forget to turn the setting back). I have been getting ~35 mpg -everywhere except traffic jams (which I often wait out, an uncommon luxury perhaps)- by driving slower than most and keeping from accelerating when I can tell I'll need to slow down. I think it also helps that I keep my foot in the same spot almost all the time, except when accelerating slightly before a hill climb. I doubt that too many people reading this post really need the reminder, but your brain is the biggest factor of the mileage your car gets... this car has been rated as getting 26 mpg highway when new. Air resistance is probably the second largest factor, and it helps to follow (safely far enough) behind other (large) vehicles and leave the windows at least almost closed. Horsepower is the measure of torque produced by the engine, ruled by your foot on the gas pedal (hp ratings give maximums), and less pressure there will increase the mileage of every car.

you all are missing it.

This was very well covered humourously in the GM vs Microsoft presentation that went around a few years ago.

Fuel economy has not improved at the same pace as electronic technologies.

If the auto makers were actually serious about fuel ecnomy, it would be happening.

The auto makers are not interested in making vehicles fuel effeicient for one significant reason.

They are in bed with the oil producers!
They have a vested interest in each other and no one else.

Think for a minute, why are we still using only petroleum based fuels.
Why are all alternative engines NOT being researched, developed and deployed?

There is just too much money to be made by the oil companies and the automakers who are creating these petroleum guzzlers.

In the 1930's we had cars that could get over 40 mpg. And they were huge and heavy. Weight is not the deciding factor in fuel efficiency. Actually attempting to get real fuel efficiency is the answer.

Yet more than 60 years later we are having troubles getting any better fuel economy or using alternative fuels.

What ever happened to the ballard power cell?
What happened to the hydrogen infrastructure.
What happened to the electric car?

The answer to the above questions is simple.
The oil companies are afraid of the competition andinstead of coming up with a solution, they squash the alternatives through political lobbying and propoganda. Through buying out the organizations that are actually making progress with fuel efficiency or alternative engines.

Give your head a shake.
I have seen the enemy, and it is us!
We have done it to ourselves by allowing the oil companies and the auto makers to continue on the merry (profitable) ways.
We have done this by sheer laziness.
Few people seek alternaives to the car.
Most are too lazy to ride a bike to work.
Many look down on public transit with disdain.
I know of very few people who choose to walk to the corner store 4 blocks away, because it is (too hot, too cold, getting dark, I am tired, etc.)

The only way that this situation could be solved is to hit them where it hurts.
In the wallet.
If we as a large group of consumers find alternatives to petroleum, they will want to capture our dollars by any means. They will develop the alternatives for us.

Auto makers should be severly penalized for Not having affordable and economical vehicles.
I mean get real, the smart car is a great idea on paper, but who can afford the retail price at nearly $30,000 cdn, to save a few bucks on gas all while also giving up passenger and cargo space.

The oil companies have no reason to develop alternatives, because they have many years of oil left in the ground.
They will wait until they are running out before seeking another fuel to sell.
They too should be severly penalized for not finding another viable enrgy source.

The problem is not the the vehicle weight or size, it still comes down to the engine.

I believe that most things happen for a reason.
Whether there is a god by what ever name, or if there is not.
whether every thing in the universe is just convenient coincidence.
I believe that there is oil in the ground for humanity to grow and learn and to develop methods of tranportation that will get the human race to the next level in the game.
Humans were born to explore and to expand our foot print.
We have touched every part of the earth, now we will need to explore out further, and that cannot be done on unleaded.

Let me get this straight...every automobile company in the world are in bed with the oil companies and have managed to successfully lobby every government in the world to supress every efficient technology ever invented? Man, if that is true, that is the most impressive conspiracy I've ever heard of. DaVinci code's got nothing on them!

I think you did make at least one valid point, though. "There is just too much money to be made by the oil companies and the automakers who are creating these petroleum guzzlers." And since the reason for the existance of any manufacturer is ultimately to make a profit for its owners or share holders, they will do whatever yields the most profit. It is that simple.

"This was very well covered humourously in the GM vs Microsoft presentation that went around a few years ago.

Fuel economy has not improved at the same pace as electronic technologies."

You're just wrong. It's not a conspiracy. There is an obvious market demand for a 500 HP SUV that also gets 200 MPG (and costs $100).

Fuel economy is bound by the laws of physics and thermodynamics.

Electronic technologies are better able to respond to the market because they're bound only by the limits of the imagination. Vacuum tubes to transistors to ICs to multi layered circuit boards and so on.

While I ordinarily wouldn't bother to respond to insane rants netizennewbie's post contains so much false information that I feel that I have to comment.

"[Auto makers] are in bed with the oil producers!"

Your argument fails in logic. The domestic automakers are losing billions while the oil companies are making record profits. If the auto makers are "in bed" with Big-Oil, they are clearly getting screwed.

"Why are all alternative engines NOT being researched, developed and deployed?"

Countless man-hours and billions of dollars have been spent by various industries, governments, and institutions to research, develop, and/or deploy alternatives, but none have yet exceeded petrol burning ICE's for their overall versatility, reliability, range, efficiency, ease of manufacture, market acceptance, and cost.

"In the 1930's we had cars that could get over 40 mpg. And they were huge and heavy. "

Where do you get that? The Ford Model A weighed less than a Mazda Miata but only got 20-30 mpg. They also only had 40 hp and were terrible polluters and horribly unsafe by modern standards.

"Yet more than 60 years later we are having troubles getting any better fuel economy..."

The average modern equivalent (mid-sized sedan) under the burden of about 1000 lbs of additional safety and convenience, make 3-5 times as much power but release a small fraction of the pollutants and get equal or better gas mileage than cars from the 1930's.

"What ever happened to the ballard power cell?"

Has not been widely adopted by ANY industry.

"What happened to the hydrogen infrastructure."

It still faces many technical and logistical challenges.

"What happened to the electric car?"

It still falls short of many of the aforementioned attributes of the ICE.

"I have seen the enemy, and it is us! ...We have done this by sheer laziness. Few people seek alternaives to the car. Most are too lazy to ride a bike to work. Many look down on public transit with disdain."

This seems to contradict your claim that it is all the oil/auto industries' fault.

"The oil companies have no reason to develop alternatives, because they have many years of oil left in the ground."

So why would they?

I am opposed to gluttonous consumption and unnecessarily large vehicles. I am a proponent of alternative, clean energy. I have no obligation to the auto or oil industry. I would buy an electric car if one were available and competitive. But nothing good can come from deranged, paranoid, erroneous rants.

I think the industry needs to change. The new GM VOLT uses a generator to charge a battery that drives a 100% electric motorized vehicle. When the battery dies the gasoline generator kicks in to powerthe electric motor. This is what we need 5 years ago. We need hydropgen or alternatives in the future.

Personally I'd like to see all cars go this route. I'd also hate seing all the Pickups go bigger...such as the Colorado, Tacoma, Dakota, and Frontier all going mid sized. If I wanted bigger I'd get a full size half ton. What I want to see is a revamped Ford Ranger mini pickup that is jacked up, geared for off road, sportiness, and equiped like the VOLT hybrid to give good MPG. Then on the opposite end of the spectrum, provide half tons with a diesel engine suitable for towing a trailer. Diesels are currently not available in half tons, and 1/4 tons are becomming midsized when they already exist as half tons. It's crazy.

I say create a couple of 100% electric hybrid cars, a hybrid mini van, a small jeep size hybrid SUV, a larger hybrid SUV capable of carrying the family and tackling light off road, a small off road monster hybrid pickup like a Ranger, and create a fuel efficient diesel towable half tons. This would create a complete lineup that is fuel efficient. It would tailor to all markets. It would eliminate 3 SUVs since manufacturers now have 5 or so models. Why is there a need for 3 different full size SUVs. Create just 1 and a small very sporty Jeep Wrangler type SUV. This would tailor to those wanting 4x4 and the storage of an SUV. The large one capable of carrying many pasengers. FOr family's who need storage but not 4x4 an AWD minivan would be ideal. An entry level, mid, and more luxurious car would tailor to most people. And the 2 pickups.

Ford would be in ideal position to do the following. Their Ranger is obsolete and do to be replaced. An overhaul to a hybrid off road monster would please many people and tradesmen who don't need to tow using a half ton or larger. And for those who are upset by the fact that diesels are not available in half tons for towing, Ford could introduce this and make many happy as they currently have a good rep going with their F-series pickups.

Fords cars are also very bland and in need of an overhaul. The 100% hybrid lineup would give them the edge they need. They could keep the very reasonably priced Mustagne as their sports car. If I was in Ford's shoes, I'd ump on this. They are a company in trouble, battleing with the likes of Toyot, etc... yet their F-series pickups have a very good reputation going for them now. They should improve the pickups to easily dominate this area, then overhaul the rest to try and compete with Toyota.

let me tell you, I'd be the first to buy a fuel efficient off-road capable Ranger. I need a pickup truck, but I don't tow a trailer, and I love the small size of the Ranger. I'd love to see it lifted, given larger tires, kept narrow, and given a hybrid 100% electric drivetrain just like the GM volt.

It makes no sense to me how American car companies (and really a lot of other car manufacturers) continue to increase HP. We are in an era where muscle cars are being released which makes no sense to me. I mean, some get OK mileage, but it doesn't make sense.

Higher mileage is not that difficult to achieve. You can condense electrical components into one "computer" that handles your audio needs, and a GPS can be VERY good for saving fuel. If our cars where more aware of their surroundings they could make better use of fuel by avoiding slower routes, traffic jams, and anticipate changes in terrain and altitude for better economy.

I think car manufacturers need to solve the marketing problem of bigger=better. I think we need higher torque, higher compression, turbo charged cars to get more bang out of the fuel. We need higher gears! I think a govern can be good if it doesn't limit the safety of the car. Tires, aerodynamics... all that can add up.

I think something that would help increase fuel efficiency is to offer an alternative to the SUV. People buy cars and thing "we need the space, we have a big family". That's bull in most cases and they end up being driven by one person to work everyday. You can live comfortably in a smaller house and have a more enjoyable experience in a smaller car. But you need to plan for this societally... Build dense cities that have a better quality of life that rely less on cars. Offer people the option to belong to a "big car club" where you can borrow an SUV any time (with a little planning) if you need one. Come up with a way that not everyone on the planet needs a car. Transfer the miles to more fuel efficient cars and make the big ones available when you need them. I think there needs to be a change in how we use and purchase cars.

The writer's fixation with the issue of electronic gadgets in cars is a waste of his time and energy (does that count as a pun?).

Your basic sedan (Civic, Corolla et all) has around 140 peak HP, that's 104,400 watts! I doubt the 100 watt stereo or DVD will have any measurable effect on millage.

Even assuming that you are driving at a constant 60mph (e.g no acceleration) your engine is probably running at about 20% of peak power. So your driving on the highway getting 34 mpg and using 21,000 watts of energy. The extra couple hundred watts the electronic gadgets are using might reduce your millage by 0.32 mpg or less than 1%.

Don't get me wrong, I think something needs to be done - but focusing on electronic gadgets is not constructive to the effort. When there are ways of achieving much greater saving with much less sacrifice of comfort.

Ugly as all get out but my parents are highly interested in this idea to get around locally and to and from work (20 miles).

The Air Car ;-)

http://www.popularmechanics.com/automotive/new_cars/4217016.html