Should I Buy a New Car?

Written by terrapass


This week’s question from Tom Wilson…

> OK, I realize a car’s major carbon footprint is the actual gas that it uses. What is the carbon footprint to just build a new car before it uses any gas?

> Am I shrinking my footprint by not buying a new car? The last new car I bought was a four cylinder, five speed manual transmission, four door sedan purchased in August of 1987. It still averages 22-24 mpg and I drive it 5-6 thousand miles per year. Equivalent new cars average 27-30 mpg.

> Should I stick with my plan? Being car payment free since 1992 is enjoyable.

Can you help? Answers in the comments section, below.

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  1. Rob Ewaschuk

    I think it was on this site, but somewhere in the past I saw a simple rule of thumb that, on average, over the lifetime of a car, 10% of its total energy consumption is embodied energy.
    For cheap-to-make long-lived gas guzzlers (think jeeps, I’d guess) it’s a smaller number; for expensive to make gas-sippers (think prius) it’s a higher fraction that’s embodied, but hopefully that’s a place to start from.

  2. Adam Stein

    Am I allowed to answer these questions? Tom, it really looks like you should hold onto your car, because you don’t drive it enough to realize a big environmental benefit from buying a new one, particularly if you only trade up to a car that gets 27-30 mpg. By my calculations, you’ll only be saving about 900 lbs of CO2 per year, and it will take many years for that to “pay back” the environmental costs of building the car.
    More importantly, there’s the opportunity cost of that money. For much less than half cost of that new car, you could probably make a variety of efficiency improvements to your house that would not only pay you back in energy savings, they would make a much bigger dent in your carbon footprint. This is just a guess, but better insulation or maybe a solar water heater would likely be a far better outlay for you.

  3. Eric Edward Carlson

    If a car is not an emotional investment for you it’s best to hold onto what you’ve got, per the previously two commenters. Adam makes the good point regarding the cost and benefits of improving your home versus a car purchase. Sometimes, I wish I didn’t like cars as much as I do; it would make being green simpler.

  4. Misanthropic Scott

    I’d also chime in on the side of not replacing a vehicle for such a small improvement in mileage and such a small number of miles per year.
    One thing to consider to be greener would be whether you could drive even less if you had a good bicycle. Bikes give a bit of good exercise, enjoyable transportation, rarely get stuck in traffic, and burn only as much carbon as it takes to feed you.
    For anyone with any form of public transportation nearby, folding bikes can be ridden to the station on one end, taken with you, and then ridden to the final destination on the other end. This would be a good way to use the bike as transportation for longer distances than one may reasonably ride.

  5. Martha M

    One more consideration: When you buy a new car, your old one doesn’t come off the road–someone else buys it and drives it, and someone else drives THEIR old car…until one gets junked.
    So, buying a new car means ONE MORE CAR in the world, contributing to the carbon load. I just can’t justify trading in my perfectly good 16-yr-old Volvo 240 wagon (4-cyl) that seats 7 if needed, and gets up to 28 mpg on the highway…

  6. john kurmann

    Hi, Tom. Though I basically agree with the previous posters about the limited climate benefit you’d see by buying a new car given how little you drive, that’s not the only consideration. Automotive safety technology has come a very long way in the last 20 years, beginning with the availability of 3-point seatbelts and headrests at all seating positions, the development of crumple zones to absorb crash impact energy, antilock braking systems, front airbags, seat-mounted and curtain side airbags, and vehicle stability control. Emission controls for smog-forming air pollutants have also improved a great deal in the last 20 years, so a new–or much newer–car would contribute significantly less to air pollution.
    And you could buy a hybrid which would get far better than 27-30 mpg while providing the same utility as your current sedan. If you bought a distinctive hybrid like a Prius or the forthcoming Honda Insight, you’d be sending a clear signal to everyone around you that reducing your energy use is important to you. Those kinds of signals play a crucial role in social change.
    In the end, of course, it’s up to you to decide what your highest priorities are with regard to your vehicle and finances.

  7. Chad

    It almost is never a good idea to scrap an old car to buy a new one, in environmental terms, unless you drive more than 25000 miles per year and are willing to switch from a big inefficient vehicle to a small hybrid. A general rule of thumb is that holding on to your own car will save you about $3000 per year. How many Terrapasses can you buy with that much money? Enough to offset 100% of your old car’s emissions fifty times over.

  8. Jackie

    I am driving a 1982 Honda Civic Wagon. It gets 35 mpg reliably, and up 40 mpg if I keep it down to 60 on the highway (which I am still doing even as gas goes down). I would only buy a car if and when I can no longer drive the old one – it’s hard to find parts these days, and I am thankful for a wonderful mechanic who tinkers and makes it work. For a while I had a 1990 Honda Civic hatchback that got 40 mpg. I loved that car.
    If I were to need a new car, it would be a car with great mpg. Probably a Honda again. I also wonder why the newer cars (even some Hondas) don’t the mileage of my old car. Anyone know?

  9. john kurmann

    Hi, Jackie. Part of the explanation for lower MPG in many modern cars is that they have much more powerful engines than your ’82 Civic wagon or your previous ’90 Civic hatch. Americans like rapid acceleration, and that comes at a price in lower fuel economy.
    Modern cars tend to be larger than they used to be, too, so they weigh more. For example, today’s Toyota Corolla is larger than the original Toyota Camry, which has grown to accomodate.
    Also, modern cars have many more amenities (power everything, better stereos, climate systems, standard A/C) and safety features (headrests and 3-point seatbelts at all positions, antilock braking systems, front and side airbags, and, most recently, vehicle stability control in some models) than either of the cars you mentioned, all of which add weight. This does make them more comfortable and much, much safer, however.

  10. JD Howell

    Wow, lot’s of great posts here… especially the one regarding a bicycle. Of all the good things to recommend, a bike is the best. Many people overlook the folder concept, but there are great ones being built right here in my own backyard (Bike Friday). We own three and my personal BF is a ‘Speeding Tikit’… stealth black, fast folder, 27 speeds, sexy.
    Having listened in at the recent Energy Roundup in Eugene, OR, a community forum on many sustainability issues, it becomes evident that the first post is a reliable best bet as well. With over 40% of GHG’s being emitted by our buildings, we really need to button them up and reduce our footprints both at home and in our places of work.
    So if you did both of these, and with the option of electric bikes if pedaling is too difficult or your terrain is hilly, adding solar pv and/or thermal, combined with efficiency upgrades, the choice of public transportation, and even walking for certain local needs… all add up to a more socially improved planet whose citizens are healthier, have more time to socialize, and slow down to at least remember the visit !
    As for me and mine, we’ll see you out there, on our bikes of course… JD Howell, Eugene, OR

  11. WheelScene

    Buying a new car means ONE MORE CAR in the world, contributing to the carbon load.

  12. marlene

    I read somewhere that the energy cost of producing a new car far exceeds the energy cost of driving it during its lifetime. Does anyone have more specific info on this?
    We have always driven old used cars to their graves. My first car, a Datsun, got 30 mpg and was stolen with 109,000 miles on it. None of my subsequent cars has gotten such “good” gas mileage. I have never bought a new car and never will. I think the federal bailout of GM is a poor idea unless they start producing high mileage (50+ mpg) cars exclusively and unless they fully enter the business of retrofitting their old cars to be as energy efficient/green in as many different ways simultaneously as possible. For example, why doesn’t GM offer solar panel roof/hood retrofits–and maybe some rooftop small windmills that turn as you drive? Several ad-on’s might be able to make the first 20-30 miles of every roundtrip totally green, and since most people’s trips are under 30 miles roundtrip, then using any car (new or old) would feel nicer. I have in desperation cut local trips as much as possible, not because I can’t afford the gas, but because I choose not to waste fossil fuel/NOX pollution on ground transportation. Hanging on to old cars and never buying new is the best strategy I have been able to think of for an industry that can’t or won’t get better mileage since well before the first gas crisis in 1973. I could care less about most “features” they advertise, including GPS (well, it would be nice to have one cupholder and space to put my purse without straining to reach it in the back seat).
    If GM and Ford could turn every old GM/Ford car into an electric and alternative fuel car as well as a gas guzzler; then this would demonstrate that their managements have some real ability to think creatively. Until then, I am still driving a used 1978 Mercedes coupe and a 1982 Mercedes wagon with one after-market AC. Just my non-techie take. The other crucially important car issue for us is the absolute comfort of the front seats. Mercedes wagons 1982-1985 had very comfortable front seats, but I do not know of any other car with such comfortable seats, including our used 1995 Lexus and used 2001 Mercedes wagon. My husband with back problems cannot sit in any car except our 1982 Mercedes wagon (the’95 Lexus is his next favorite car seat although I use a folded car blanket after an hour). We, especially, wouldn’t purchase a newer car with headrests that force your head too far forward even for safety. The safety of cars generally has probably declined over the decades as the side steel pillars into which the lap and harness belt attaches have grown thinner. I don’t think airbags make up the difference in loss of safety of the lap/shoulder belt arrangement.
    Driving far less in my old cars is one thing I can do to help the environment. And I love to drive, except in France, which has recently re-written Leibnitz to read: “the shortest distance between any two small towns is 4-6 tight, blind rotaries.” We are buying a far more energy-efficient house close to a subway and 10 minutes from a good hospital. I can’t imagine putting 26 solar panels for $23,000 under NH snow/ice for 7000 kilowatt-hours/yr and $1200/yr in electricity, but some neighbors apparently did (utilities refused to extend them service when they built their new house), and they are now selling solar panel green electricity back to the ecstatic grid.
    Money saved on buying a used car under $5-8000 is money you might use on home-heating green options. Our super-insulated house has heat-sink thick stone floors over gas-heated hot water pipes underneath. Really efficient, I’m told. Even heat and nice on the toes. No constant electric fans/blowers as with oil forced hot air and no loss of heat through long, cold cellar air ducting. It is amazing how much money one can save by changing the kind of heating system one uses and by insulating to the gills. Some unintuitive suggestions on green home construction can be found at Amory Lovins’ website at Among other things, he used a passive solar low-e windowed solarium with a thick stone floor to help heat his large home/office and made the solarium into a tropical garden. Now that’s imagination!
    To Misanthropic Scott about those folding bikes.
    Paris, Rouen, and other European cities have bikes you can rent and drop all over the city. They used to say @ 1978 that 80% of Boston air pollution came from cars cruising the narrow streets in futile search of a non-existent parking space. It was so difficult to drive in Boston that my husband gave up his downtown office when our kids were born. It took 45 minutes to walk home carrying a heavy file whenever it rained (and an hour both ways if I tried to pick him up with the car from the Pru Center!), and he almost never went to work when it snowed. He rarely took the subway because he could walk faster. He lacks the balance to ride a bike. He did suggest a large tricycle would work for him if it had an extremely comfortable seat and it wasn’t raining/snowing. Some people were not meant to commute.

  13. john kurmann

    Hi, Marlene. Wherever you read that it takes much more energy to manufacture a car than to run it over the course of its time on the road, the author was either mistaken or lying. Multiple sources have done full life-cycle analyses on automobile manufacture and use and found just the opposite to be true. The percentage attributable to manufacturing is only about 10-15% of the total energy use over the entire lifecycle of a vehicle. The Union of Concerned Scientists offers their take on the issue here:
    Current solar panels–even if covering the entire outer surface of a retrofitted car–would not generate enough electricity to justify their cost and would contribute very little to the motive power of the vehicle. Solar PV simply isn’t efficient enough to be viable for that use yet, and retrofitting in this manner would be tremendously expensive even if possible.
    Automobile-mounted wind turbines would be neither large or high enough to generate a useful amount of electricity; in fact, by increasing drag, they might do more harm than good.
    Blaming the industry for not building more fuel-efficient vehicles is a waste of time and energy. The automakers didn’t force people to buy their products, and, as long as fuel prices were cheap–which was almost all of the last 90 years–typical Americans wanted the most powerful, feature-filled vehicles they could afford. If we want to change that, we need to build the public support necessary to impose True Cost Fees on fuel (and other energy sources) to internalize their ecological and human health effects, raising the retail prices enough to drive us toward a less autocentric way of life and more energy-efficient vehicles.
    Actually, automobiles have gotten much safer over the last 30 years as automakers learned how to engineer crumple zones to absorb the impact of a crash before it reaches the passenger compartment, improved seatbelts, added cushioning airbags all around, and now are making electronic stability control widely available.
    There are actually quite a few used hybrid cars on the market, so avoiding the purchase of a brand-new car doesn’t have to mean driving an old vehicle with obsolete emissions and safety equipment. I have owned 2 used hybrids, a 2000 Honda Insight (which I wrecked in rush-hour traffic) and a 2002 Prius, which I still own.

  14. Scott

    [And buh-bye. Commented deleted for being insufficiently clever to warrant the gratuitous snark.]