Who would honestly try to use that argument?! I have to admit I don't drive, so maybe I'm just being ignorant here, but presumably people with cars also have to eat?

And what about the cost of healthcare? (Bicycle more = better health = less amount of taxpayer dollars on healthcare) We should add that to the math. I'm ok with folks not wanting to bicycle, but to suggest that it is less efficient (a suggestion that it is more harmful to the planet than driving) is not just bogus, but injurious to our society.

I guarantee I can't bike 48 miles after a half pint of vodka :-)

Our overweight population is already consuming plenty of energy for bike riding, so there is no cost to fuel the cyclist. We are storing all that fuel as fat when we don't ride bikes. Also the health benefits should account for some savings when you consider health care costs.

If cyclists carried around as much excess steel as cars, that idea might be worth looking into. But when I ride to the grocery store, I bring only what I need. If I'm not gonna stop somewhere untrusted, I leave my three pound lock at home. When an SUV driver hits the road, do they leave three tons of cargo capacity in the garage because they won't need it on that trip?

A persistent rumor claims that riding a bike is actually less efficient than driving a car if you account for the energy that goes into producing the food/drink that "fuels" a cyclist.

This doesn't make sense. The cyclist has to eat anyway so the "cost" of the "fuel" is sunk. The fuel is consumed whether the cyclist bikes or drives, isn't it? I can't imagine that a cyclist would need to eat much more food just because they're biking. This sounds really ridiculous.

It seems to me that Mr. Green misses an important point here: drivers will be eating as well. While cyclists may need to consume some extra food for energy, I'd imagine that the extra amount consumed (and the energy that goes into producing it) is only marginally more than the food consumed by an automobile commuter, if there is an overage at all.

And I know I'm generalizing, but I'd imagine that folks who make the choice to bike to work (especially those who do so on for health or environmental reasons) are likely to: a) consume foods that have less energy impact (that is to say, less beef or other land meats), and b) consume more organics.

Food is "renewable" and gasoline is not.

Expense? A hard ride goes about 1000 calories an hour give or take. That's about 20 miles (again give or take). I eat well at about $1-$2 for 1000 calories. Compare that to $4 for the gallon of gas to go 20 miles.

Ethanol is another renewable energy source (well, really the sun is the source, the corn/ethanol is the stored form). But that is being manipulated by profiteers and also it's only an additive.

There are many possibilties for human-powered vehicles -- the upright bicycle is just one. I'd like to see more of them.

Your body is far less efficient at turning fuel into energy than a car. Pound for pound, your car is definitely more efficient than you are.

But most of the pounds in your car are absolutely wasted if the primary purpose of your car is to move your butt around. Because you're not just moving you around- you're moving this steel behemoth around. The fact that you're inside is more of a coincidence.

That said, all you two wheeled cyclists are posers! Uni FTW!

As Brett (#4) says, for most of us we're already consuming more than enough fuel for biking. If anything I eat less since I started biking to work.

The manufacturing cost of bikes of course mean they aren't energy 'free,' but obviously that comparison isn't going to come out in the car's favor.

"A persistent rumor claims that riding a bike is actually less efficient than driving a car if you account for the energy that goes into producing the food/drink that "fuels" a cyclist."

Oh please, that is such obvious bullshit, the kind of rumour lard-asses like Rush Limbaugh pump out to try and discredit environmentalists. It also sounds like a half-assed excuse for not exercising: "I'm not being lazy, I'm helping the environment!" These kinds of rumours are dreamed up to justify laziness and selfishness.

The amount of carbon pumped into the atmosphere in making a bike is a one-time expense, for a car it's a constant expense. As for the carbon produced in food production., it just seems like a backhanded way of discrediting environmentalists again, like they're trying to get to the logical conclusion: "environmentalists want us to stop eating, our food is destroying the environment!"

Our overweight population is already consuming plenty of energy for bike riding...

Driving is better for the folks at the NAPA auto parts store, for sure.

I think you've all covered the arguments, this is silly, but these types of things stick around because people are so GULLIBLE. Fore example, my mom sent me the "don't let your kids play in the ball pit at McDonalds" story again, recently.

Sigh.

Next time somebody whines at you about gas prices, suggest they look around and see how much one of their friends would charge to push their car 20 miles. Usually adds a little perspective.

ILL LICH: "These kinds of rumours are dreamed up to justify laziness and selfishness. "

Right. Laziness and selfishness don't need to be justified. They're their own reward.

But these rumors do have a value. They draw attention to the fact that your body sucks. You throw off all kinds of waste heat, barely extract any energy from your fuel (most of your fuel mass just passes through!), you have a wasteful, clumsy and impractical mode of upright locomotion. And the list goes on.

This is a real problem that barely anyone is actively addressing. Humans, designed by the process of evolution, are adapted to an environment that no longer exists. Our bodies are ill suited to the modern environment that we've created.

Down with bipeds! Down with digestion!

I forgot to raise one point against the original article. The author says that these worries are prompted by "life cycle" analysis and says, "Such analysis is useful, but really it's making lots of you think way too hard for your own good."

Perhaps he's just making a joke, but this is frequently a problem with a certain strand of environmental activism - take our word for it; don't think for yourself.

It reminds me of an ethanol activist I heard on NPR a couple of years ago. In response to a study showing that the production of ethanol still used more energy than it produced, he just said something like, "Well we know we're doing the right thing."

Obviously the supposed energy inefficiency of cycling is bogus, but the response should be to encourage people to think more, not less.

And the two gallons of Ethanol require 2.4 gallons of petroleum to produce.

Cyclists tend to be more health conscious and therefore eat foods which are less wasteful. A greasy hamburger requires a lot of fossil fuel to produce.

It is just a ridiculous argument to make. To try and talk anyone out of riding a bike, and driving instead, you'd have to be a real asshole.

What is the economic footprint of a Clif Bar?

Your body is far less efficient at turning fuel into energy than a car. Pound for pound, your car is definitely more efficient than you are.

@14:

Right on! I won't be driving to work tomorrow because it's efficient; I'll be driving to work tomorrow because it's comfortable, it's climate controlled, it requires a minimum of muscular effort, and there's a radio.

The commentary that the article is stating debunks the myth of the inefficiency of cyclists compared with cars, though as some of the comments here have stated they could have gone many different ways to make that point, ie weight of car vs weight of bike, the fact people have to eat to survive and adding gas to a car is in essence doing double, food to fuel you gas to fuel car = fuel from two sources to do the same thing as cyclist needing fuel from one source, and the list goes on. As a more recent BB post has it that cyclists in places like LA can get around a city a great deal better and faster than cars can. So it adds to the point that a bicycle beats a car, which is so common sense its surprising that people question it. Plus I bet those people using cars go to the gym and sit on a stationary bicycle to keep fit anyways ... which is more than ironic.

"Driving 48 miles takes more than two gallons of ethanol, whereas only eight ounces of liquor, a mere half-pint of vodka, can fuel a cyclist for the same distance. Happy trails!"

"Happy" trails, maybe - but for 48 miles? I would like to see this claim proven. Really. I want to see someone stay upright on a bicycle after ingesting a half-pint of vodka and then pedal the thing for 48 miles.

I believe this "persistent rumor" is fueled by Chris Goodall's claim that walking to the grocery store used more energy than driving (or at least that's where I first heard something like it).

This indeed a completely insanely stupid argument. I will consume the same amount of calories in a day whether I ride a bike or drive. And yes, even if I am biking 50 miles, I will not consume significantly more calories than if I sit on the couch or drive my car. In many cases, Iwill consume MORE calories when I'm given the opportunity to sit around and do nothing. Whoever came up with this is an utter asshole who deserves to be drowned in their own cheeseburger-shit.

I bike every day to work here in Los Angeles. But can I just say I ran into the Critical Mass group [while driving] up in Berkeley and they are a silly bunch. They protest by blocking all lanes of traffic and letting no one go by. How can you convince anyone to consider bicycling if your actions only piss drivers off? Doesn't work.

That said for short distances cycling is better, more efficient and smarter. Just don't block automobile drivers when doing it.

Another difference in costs that can be considered is that of injuries.

Accidents happen, but the fatality rate is much higher for both drivers and pedestrians when you involve 12 tons of steel traveling 25+mph.

@t3knomanser, according the the Sloan Automotive Lab at MIT, today's cars one use 1% of the energy contained in a tank of gas to propel driver forward. 90% is lost between tank and wheels and the other 9% is used to propel the mass of the vehicle.

The human body and the modern bicycle are far more efficient than that. Plus, I don't idle as high as a car when I'm at a stoplight.

If you ride a bike, you will burn more calories than if you are stationary, but that is minimal. In addition to the previous points, I would like to point out that if you are active, your body will become more efficient. It will actually squeeze more energy out of the food you eat, and your muscles will adapt for endurance (see white meat versus dark meat).

Though this argument has lots of problems, life is also much more than a calorie balance sheet. If our towns and cities where built for walking and biking as well as driving, quality of life and daily experience would be a bit more human-scale, and I think, generally better.

@ #9 posted by t3knomanser:
"Your body is far less efficient at turning fuel into energy than a car."

Please tell me this is a bad joke? Here's a quick comparison for you. One US gallon of gasoline contains about 31,500 calories. A person running a marathon (26.2 miles) consumes roughly 3,000 calories.

"Pound for pound, your car is definitely more efficient than you are."

Oh, I see. Something that is inefficient but really really heavy wins.

On the bike, I get at least 53 miles per burrito. Let's see Toyota top that!

"persistent rumor" = talking point in a FUD campaign.

Like the one about the manufacture of solar panels consuming more energy than they'll ever produce. Or evolution violating the second law of thermodynamics.

* * *

I'm seriously considering getting a bike for commuting. The weather here (Portland) is amenable to bike commuting maybe 8 months a year.

Biggest fret is working out a morning routine . . . do I shower and get dressed at work, or hope the ride doesn't sweat me out?

I can easily afford to burn a few more calories. If I actually need to eat more, it would be in the form of Ramen noodles at lunch.

Patently false. Get on a bike and ride till you run out of gas.

It takes about 6lbs(1 gallon) of fuel to move 1 ton 20 miles. Let's say you can travel the same distance on 4 Snicker's bars. Off the top of my head, I don't recall what that weighs. Say each snickers bar is 4oz, that's 1lb of fuel to move .10 tons (if you're big boned anyway).

That's 1/6th the fuel for 1/10th the work. Car wins.

@nolongeranon: no, it's about work. Work is force * distance, and force = mass * acceleration.

More mass moved across the same distance is more work. More work for less energy is more efficient. Ergo, your car- which weighs more than 10xs the average marathoner undergoes more force. Ergo, more work has been performed and at a lower energy cost per joule of work.

As I said earlier- the issue with a car is that nobody really cares about the car getting from place to place. The car exists to get you from place to place. So if we remove the mass of the car from the factor of work (since we don't care about the car), then YES- cars are inefficient.

The point I'm making is that you shouldn't use your car. That's a waste. Your car should be free to roam as it sees fit, because that's far more efficient than letting you roam as you see fit.

A large part of the inefficiency of cars is the inefficiency of combustion engines, which only convert like 15-20% of potential energy. Fuel cells are considerably more efficient, converting closer to 80%. Biking should still come out well ahead, but the margin will be narrowed.

"On the bike, I get at least 53 miles per burrito."

And you probably give back more gas than you consume.

This reminds me of the BS argument that disposable diapers might be as good an option as reusable diapers. Merely posing the question insults our intelligence.

That is complete crap. I stopped driving a year ago, and I eat LESS than I did when I was driving. I might drink a couple more glasses of water a day, but that's out of the tap, not bottled.

@ t3knomanser

Do you mean our bodies are less efficient at converting calories to KINETIC energy for moving around? Because the calories we ingest aren't used exclusively for mobility. I don't know what the actual numbers are, but if you take basic bodily functions out of the equation, it will look much different. I'm sure your f/u question will be, "well, doesn't the body NEED the functions in order to be mobile?" Sure, but doesn't your car need upkeep too? How do you figure those things into the equation?

Eh...I don't think either of us really have numbers to back this up. I just think you can't say "a car is more efficient that a human body." Besides, we're talking about energy required to move a human, not a human AND a car.

@ t3knomanser

"It takes about 6lbs(1 gallon) of fuel to move 1 ton 20 miles. Let's say you can travel the same distance on 4 Snicker's bars. Off the top of my head, I don't recall what that weighs. Say each snickers bar is 4oz, that's 1lb of fuel to move .10 tons (if you're big boned anyway).

That's 1/6th the fuel for 1/10th the work. Car wins."

This doesn't really mean anything. First, it's pure conjecture. Second, why are you talking about weight? Why don't you talk about CALORIES?

According to the wrapper on a Snickers bar, there are 271 calories per 2 oz bar. We'll assume you're right (you're not) that it takes four snickers bars to go 20 miles. That's 1084 calories.

A gallon of gas contains about 31,000 calories.

And since we're talking about the energy required to move a HUMAN, not a CAR, riding a bike saves 29916 calories. Even if we use your logic, the car at 31,000 calories/20 miles is still less efficient than biking at 1084 calories/20 miles * 10 factoring in your weight estimate.

Car 1550 cal/mi
Snickers Bike 542 cal/mi (with weight factor)

(I'm doing this on my lunch break, so I apologize if I screwed up the math at all)

t3knomanser @ 32: It takes about 6lbs(1 gallon) of fuel to move 1 ton 20 miles. Let's say you can travel the same distance on 4 Snicker's bars. Off the top of my head, I don't recall what that weighs. Say each snickers bar is 4oz, that's 1lb of fuel to move .10 tons (if you're big boned anyway).

I'm trying to come up with a polite phrase for "making up figures out of thin air and then treating them as fact" and not having much success. So let's start with "you're assuming facts not yet in evidence" and go from there.

One Snickers bar weighs 2 ounces, not 4 (for starters) and contains 280 calories (source).

Bicycling consumes somewhere in the range of 25 to 40 calories per mile (source).

Bicycling 20 miles would expend roughly 500 to 800 calories, which is 2 to 3 Snickers bars, which is 4 to 6 ounces of fuel.

If I'm calculating correctly, that means it's either:
.25 lb fuel to move .1 ton 20 miles = 2.5 lb fuel to move 1 ton 20 miles
or
.375 lb fuel to move .1 ton 20 miles = 3.75 lb fuel to move 1 ton 20 miles

That's 1/6th the fuel for 1/10th the work. Car wins.

auto: 6 lbs fuel / 1 ton / 20 miles
bike (low): 2.5 lb fuel / 1 ton / 20 miles
bike (high): 3.75 lb fuel / 1 ton / 20 miles

Unless I've miscalculated, your assertion that the car is more efficient is patently false.

[on preview: crossposted with RacingChikin, whose calculations also show that your argument is bogus]

@RacingChikin: because calories are not a unit of work. Calories are an (antiquated) unit of energy, specifically heat. Joules are the SI unit of energy, including heat but- important to this case- mechanical work.

Which is what I'm discussing. Engineers use input energy and output work to discuss efficiency.

"And since we're talking about the energy required to move a HUMAN, not a CAR"

No, we're not. We're discussing which produces the most work for the least energy. Car wins, easy. If you deem the mass of the car as unimportant, then yes- you're entirely right.

Which goes back to my previous comment: you should sit at home, and your car should be free range. It's more efficient about using energy than you are. If we abandoned people entirely, we'd save far more energy than merely abandoning or restricting our use of cars.

@Lexica: you move one ton on your bike? I think not.

Concentrating on a localized, limited occurrence blinds to the long range consequences of shifting into a rutinely less consuming model, couple this with working at home (remote office) and-or better placed work areas (where the first option can't apply) the results just wouldnt compare. So we should not be looking for the isolated successful individual but a widespread socioeconomical lifestyle. Without a decisive economical engine, the model fails.

t3knomanser # 41: you move one ton on your bike? I think not.

Please reread what I wrote:

.25 lb fuel to move .1 ton 20 miles = 2.5 lb fuel to move 1 ton 20 miles

If it takes X amount of fuel to move .1 ton a specified distance, then it takes 10X amount of fuel to move 1 ton the same distance.

It's careless at best and dishonest at worst to use different units of measurement when comparing things to each other.

From a recent Dirt Rage article: "The bicycle is the most efficient machine ever created: Converting calories into gas, a bicycle gets the equivalent of three thousand miles per gallon." -Bill Strickland, The Quotable Cyclist

My cruiser bike has more than 3000 miles on it at 5 years old - had to replace a hub already.

Our local bike week uses 733mpg and Free Coffee as our poster/shirt slogan. Think the coffee might add to that...:)

www.bonedalebikeweek.com

hey t3knomanser:

I have moved one ton with a bike, and so have some of my friends.

Not the easiest thing in the world, but not impossible and definitely not deserving of an "I think not" dismissal.

www.pedalersexpress.org

We do 600-lb loads on a regular basis in Eugene, OR.

Here's the reference we need. Humans are surprisingly efficient at turning fuel into mechanical work (~20%, if memory serves), considering the relatively low operating temperature.

Internal combustion engines aren't all that efficient (in the 20% range, but it's far below the Carnot efficiency dictated by their operating temperature).

Even if you look at it in terms of kcal per mile per lb, the bike still wins. Consider a car of 3000 lbs vs a bike + rider of maybe 200 lbs. Rough numbers, but we're talking a 15:1 ratio. The ratio of energy expended for a bike @ 15 mph vs a car @ 30 mph is over 22x, so the bike still wins. It's close, though.

Of course, with a bike you don't need so much mass to get places.

A separate issue is how much energy is expended to get your food to you than to deliver and burn a gallon of gas. If you eat factory farm meat flown fresh to you daily, the energy input per energy provided to you might not be so hot. If you stick with some oatmeal, you are in good shape.

t3knomanser- you are all over the place, sort of right, moreso wrong. For starters, calories and joules are both units of energy. Different units of measure, that's all. Mechanical work is a type of energy, as is heat. You can express mechanical work in calories and thermal energy in joules. No problem. There are fungible as much as the 2nd law of thermo lets you convert one to the other.

You were getting at input energy (total thermal) vs output energy (mechanical), the difference being dictated by efficiency, which is relevant, but you didn't do anything with that. Also, what really matters is energy in vs. mass of payload vs. distance moved. Payload defined as what needs moving, less the mass of the stuff used to move it (i.e. car or bike). Including the mass of the vehicle in the efficiency calc. tends to favor heavy vehicles, b/c so much of the energy input goes to aero. drag, which is not a direct function of mass. It is indirect, as heavier things tend to be bigger, but the drag goes as area (length squared), and the mass scaled with volume (length cubed), so all else equal drag goes to the 2/3 power of mass, so bigger vehicles seem more efficient even as they use more fuel to carry the same payload. A Hummer may well look better in terms of energy per lb. per mile than an Accord or something, but that's irrelevant if you're just carrying a single person around.

According to studies funded by energy companies, standing motionless all day also creates more pollution than driving around all day in a car.

If you really care about the environment. Drive around constantly burning fossil fuels.

Oh yeah, and don't forget... global warming is still a "raging" debate among the world's top scientists, so don't take that seriously either.

I'm not going to touch the bike v. car thing, but for another set of data points on ethanol, go look at the EPA's mileage figures for identical vehicles with gas engines vs. E85 engines. The example above credited ethanol with 24 MPG, which is extremely generous -- try 10 or 11. Ethanol vehicles get around HALF the mileage of gasoline ones, pound for pound.

Add in the amount of gas it requires to make, and ethanol is arguably the biggest con game of all time.

And just think: the US government subsidizes it to the tune of billions of dollars.

Ethanol is an ecological catastrophe, an energy policy catastrophe, and a food policy catastrophe.

@syphax - finally, someone twigs to the point I'm trying to make. The car is the payload, you're the dead weight. Your car shouldn't need you- you can barely stand up straight! Bipedal locomotion is novel, but it's just a fad.

In all seriousness, I don't have a horse in this race. I don't own a car or a bike. Bikes are for sissies that want an extra wheel for no good reason. Unicycles uber alles!

//That was the real reason for all of my comments.
//Bicyclists suck.

Just to add fuel to the fire, keep in mind that a food Calorie is equal to 1000 thermodynamic calories.

So a gallon of gas contains about 35 MJ and that 2 ounce Snickers Bar has 280 food Calories, or 280,000 calories, or 1.17 MJ.

I'm for walking and bicycling where I can, and I'm researching adding electrical assist with solar charging to my bike. Adding some panniers so I can haul a useful load should greatly increase my useful range about town.

Do they mean to imply that a person driving a car doesn't need to eat food?

I wrote a parody of this absurd argument in 2006, which I guess was too deadpan for our readers: http://wweek.com/editorial/3233/7681/

One thing which is confusing me - a few times the figure of one gallon of fuel to move a car 20 miles has come up.

Even allowing for the difference in gallon sizes, I get around 40 miles/gallon in my car (more in UK gallons). Just how inefficient are these cars you're driving?!

Like all life cycle analysis, it gets people confused. The Mr. Green article is one of the worst attempts at refuting the claim I've seen, using orange juice.

What people are really pointing out with this analysis is how much fossil fuel is used in producing our food.

And that's 1.1 gallons per person, per day. Some for fertilizer, some for tractors, some for processing, some for shipping, etc. When you map that to calories it's 10 Calories of fuel for each Calorie of average food, and 40 Calories of food for each Calorie of beef.

Now these are the hard numbers, hopefully not too much dispute there, other than to same some foods are grown much more efficiently (like open range grass fed beef) and some much worse, but these are the totals, and the average.

So yes, if you work this out, it does show that walking 10 miles on beef burns a gallon of petroleum, and that is more than driving a hummer 10 miles. And yes, that accounts for the fact that people sitting in cars consume calories to sit and people walking consume MORE calories. This is based on the more calories.

But again, the lesson here is not "get in the Hummer rather than walk." The walking has many other benefits, and there are many other issues. The real lesson here is to understand how much fuel we use for agriculture. Agriculture, especially cattle, emits more greenhouse gasses than cars. That's the lesson.
How your food is made is important.

Yes, on the raw numbers, a person who chooses to walk somewhere they would otherwise have driven, and who would not have walked or otherwise exercised to burn those calories, and thus consumed more food because of the walk -- that person is not reducing consumption of fossil fuels significantly. But few people are that person.

"Just how inefficient are these cars you're driving?!"

extremely inefficient. Up until recently, we have been paying very little for gas, which created our culture of fossil fuel addiction, and hence extreme waste and carelessness.

@ #33 posted by t3knomanser:
"no, it's about work. Work is force * distance, and force = mass * acceleration."

So far, so good. Yay physics.

"More mass moved across the same distance is more work."

And here is where it falls apart. Take this simple example: Let's say Bob pushes a bicycle with 1 Newton of force, and Alice pushes a car with 1 Newton of force. After one mile, Bob and Alice have performed the same amount of work. See that? W = F*d. Work is independent of the mass of the object.

So, unfortunately, the rest of your conclusion is invalid. Seems a bit like "a little knowledge is a dangerous thing".

@t3knomanser: Yeah, unicycles pull the chicks even better than bicycles and tight pants :)

BTW electric bikes probably win hands down, wells to wheels, and are pretty fun, though you look almost as dorky as a unicyclist.

I am Ironman.

@ #58.

For real. I've got the Ford Explorer Arc-Reactor Edition.

#56 posted by nolongeranon:

See that? W = F*d. Work is independent of the mass of the object.

... but go ahead, tell us you were being sarcastic. :)

0.3% of fuel used in cars actually moves the driver.

All the fuel in a Cyclist, moves the cyclist around.

And if people try and nimminy piminniy about that , well then they are arseclowns.

The fact that someone would even consider this argument beggars belief. And shows the level of idiocy that "fuels" the pro-oil/anti-green lobby.

Padster,

well, but only on BB would people use it as an excuse to show off their mad maths skillz. I think its awesome...outside of its political context, of course.

I thought the argument was that cyclists tend to live longer than drivers. Dying is, of course, the most energy-efficient thing you can do.

@ #60 posted by brainologist
"but go ahead, tell us you were being sarcastic"

no need, I wasn't being sarcastic.

In physics, mechanical work is very specifically defined with units of Joules.

1 Joule = 1 Newton * 1 Meter.

1 Joule is the work done when an object is moved 1 meter by the application of 1 Newton of force in the direction of motion.

By it's very definition, work is independent of mass.

You correctly pointed out that F=m*a, but then promptly ignored "a".

If acceleration is constant, then yes, work is proportional to mass. However, if force is constant (as in my previous example) then acceleration is inversely proportional to mass, and work is independent of mass. See now?

@ #65 posted by nolongeranon

Just to clarify: I only took issue with your statement that "Work is independent of the mass of the object." In your original statement (#56), you correctly responded to #33, who said "More mass moved across the same distance is more work." You are correct that more mass moved across the same distance is not necessarily more work.

However, it is not the case that work is independent of mass. In your example, you may have set it up so that the same amount of work could be performed on two different masses, but this does not mean that the two are independent. For work to truly be mathematically independent of mass, you would have to be able to freely vary the mass and have no effect on the work (all other terms held constant). This is clearly not the case.

So, while work may be independent of a lot of things, like, say, the color of the car or the scent of the air freshener, it is not independent of its mass (all other things (distance and acceleration) remaining equal).

nolongeranon is correct, but it doesn't really matter in a real world example. Assuming a car to bike mass ratio of 10:1, then the person pushing the car with the same force as the bike will arrive at the same destination around 10 times later (including various assumptions about constant acceleration, and deceleration, etc etc) The efficiency of the car compared to a bike is not really the issue. Or it shouldn't be.

If you ride a bike, you will use less energy overall than if you drive a car. Gross energy usage per person is going to be lower. Even if you eat 10-15% more food calories than a driver. Compare the energy used to get you were you want to be, in raw numbers, (and include the calories that the driver eats, unless its acceptable in this comparison for the driver to starve to death), forget dividing them by the mass of the vehicle. Thats the message thats important. Use less energy. All this other stuff is just obfuscation.