Our Cars’ Weight Problem

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Robert Norton:

the new mandate that all auto manufacturers achieve by 2025 a Corporate Average Fuel Economy (CAFE ) standard of 52 miles per gallon — twice the previous requirement of 26 miles per gallon.

At first blush, 52 mpg sounds like a laudable goal. What’s wrong with making more efficient cars? After all, they’ll be more affordable to drive, and simultaneously reduce the nation’s carbon emissions. Talk about a policy twofer!

The problem with the goal is simple: We can get only so far on the mileage front without affecting safety. Allow me, as someone who has spent a lifetime in and around the automotive industry, to explain why.

To get to where the government wants us to be, we start by employing all the engine technology possible to extract every last mile per gallon. This means using direct-injection combustion, variable valve timing, and sophisticated air management that includes more turbo-charging, as well as fine-tuning the engines with the use of sophisticated sensors and algorithms. The industry has done all of that, and today’s engines are impressively efficient.

We next turn to transmissions. These can help save fuel by allowing the engine to run at lower revolutions per minute (rpm). Think of being able to shift gears on a bicycle as you go up or down hills. This helps you get more from each pedal stroke. It is the same for vehicles. Today’s vehicles have progressed far from the original two-gear automatic transmissions; some offer as many as eight gears that automatically maintain engine rpm within a certain range. This has all been done, and the miles per gallon have improved accordingly.

However, all these efforts are not nearly enough to achieve the mandated 52 miles per gallon. So what else can be done? It’s what I call Jenny Craig engineering: reduce car weights, and reduce them massively.

It is a simple matter of physics: It takes less energy to propel a lighter object at a particular speed than a heavier object. You may wonder why so many vehicles suddenly stopped carrying a real spare tire years ago, or why there is so much plastic in vehicles today. Wonder no more: It was for weight reduction.

This is not a new trend; weight-reduction efforts have been ongoing since Jimmy Carter was in office. And they are not aimed just at larger vehicles. The Toyota Prius is slated to shed 500 pounds.

But less weight is a good thing, isn’t it? Well, not always. Why does professional boxing have weight categories that place athletes in competition with others the same size? Why is the NFL so concerned about the head injuries that seem to be happening with more and more frequency as players get bigger and faster?

Because size matters — and we all know it. Take this simple test. Imagine a head-on collision on a two-lane country road at a speed of 40 mph. One of the cars involved is a Cadillac Escalade and the other a Chevy Volt. Which would you want to be in? Which would you want your child in?

In a Cadillac minute, you would choose the Escalade. Because you don’t need to be an automotive engineer to know the big car will crush the small car. The driver in that little car will in all probability be severely injured, maybe killed. You, the driver in the Escalade, may walk away unharmed, or with only minor injuries.

Why? Once again, it’s physics. The force of something heavy and big crashing into something small and light leaves that something much, much smaller.

The same goes for that big heavy vehicle crashing into something stationary, like a wall or a tree. Or something pretty mobile — like a deer — crashing into the vehicle.

Bigger and heavier is simply better when it comes to car crashes, all other things being equal.

We do not have to speculate about the safety ramifications of being in a smaller vehicle; the Insurance Institute for Highway Safety (IIHS) ran a rather expensive series of tests in which it pitted a smaller vehicle against the next size larger vehicle from the same manufacturer. Specifically, they ran a Honda Fit into a Honda Accord, a Toyota Yaris into a Toyota Camry, and a Mercedes C Class into a Smart Fortwo (owned by Mercedes).

Care to guess at the results?


There are approximately 42,000 motoring fatalities each year in the United States. That is a large number, and it has remained stubbornly at that level. Why, with all the technological innovations that have occurred in so many key areas, such as electronic stability control, anti-lock brakes, and air bags, have we not reduced those numbers significantly? The major reason, I believe, is the smaller vehicles our government has been pushing in order to support the environmental agenda.

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6 Responses to “Our Cars’ Weight Problem”

  1. 1

    Nan G

    Our Mini Cooper has an on-board gas computer that allows you to see how much MPG you are getting over the tankful ….or at any one second.
    Usually I set it to the tankful….the average changes as I go through the tank on city streets or freeways.
    BUT I also set it to the real-time use to help me improve MPG in various driving conditions.

    Official CAFE standards are NOT real world AT ALL!
    Only downhill at best MPG can most cars get what the company claims.

    In real life the MPG suffers most in bumper-to-bumper freeway traffic.
    A car, like mine, that CAN get 43MPG on the open road, will be getting only 7MPG during rush hour.
    So, all the engineering in the world won’t help cars use less gas as long as there is congestion on the roads.

    The real issue with Obama’s impossibly high CAFE standards is that people will be getting KILLED because of them.
    And as Biden pointed out about Obama’s views:
    “As the president said, if your actions result in only saving one life, they’re worth taking.
    Yet Obama is going in the OPPOSITE direction as regards cars and CAFE standards.

  2. 2


    Here are some curb weights for the Ford Mustang over the years. I used the base models, with the smallest engines etc for all years. Use that as a benchmark for a mass-produced 2-door.

    What you see is that cars got lighter when the oil shocks started happening and MPG became more of a worry, but then things got heavier as we start adding airbags, big stereos, electric windows and seats, frame reinforcement etc.

    Year Weight (lbs)
    1967 2758
    1974 2620
    1980 2300
    1990 2715
    2000 3064
    2010 3350
    2013 3523

    A Honda Civic weighed 1731 lbs in 1980. The current Civic is 2740 lbs

    So when you think about it, fuel efficiency has actually skyrocketed when you take into account that cars have fattened up by at least 50%.

  3. 3

    Nan G

    Great point.
    Seems almost every pound of that extra new weight was mandated by gov’t requirements for safety.
    Air bags, padded dash, reinforced frames, etc.
    It wasn’t like the newer cars are covered in chrome.

  4. 4


    Not only all of the above, but the new fuel economy standards include light trucks. So, Mr. contractor, say goodby to your pickup trucks. They will either not be manufactured at all, or be so light, flimsy and underpowered that they will be useless as a working truck.
    I love my two-ton Caddie Fleetwood. Lots of interior space, lots of cargo area, great ride. Crappy fuel mileage, but I’m willing to compromise.
    Easy to tune up and repair when it needs it, also.

    Oh, and if your car has air bags and you plan on keeping it for a while, you’ve got a financial time bomb built into it: http://spectator.org/archives/2012/02/27/the-ticking-time-bomb-in-your
    This will, of course, hurt the poor the most as the supply of cheap used cars dries up over the coming years. Just another unintended consequence of overreaching regulation.

  5. 5

    Nan G

    That’s a terrific article, Petercat.
    This is a chart from Dec 2012 about how OLD our durable goods (including cars) are getting in America.
    Those lines are AVERAGES!
    That means 1/2 of all cars on our roads are older than the 4+ years.
    Your air bag issue is a real one.

  6. 6


    To put everything on an even basis and to allow for continued safety, the MPG should be figured on a per pound basis. You can still have a 4000 lb car for safety, but just have the MPGPP (miles per gallon per pound) improve. an example, that 2300 lb Mustang at 25 mpg is 92 mpgpp. at the same 25 mpg with the weight now up to 3500 lbs you are up to 140 mpgpp. that’s a 52% improvement. pretty remarkable

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