Driving, The Third Option

Several years ago I was listening to a feature on NPR talking about how people could not trust the fuel efficiency numbers published by the EPA. There were all kinds of moaning and complaining about how the sticker did not match real world experience.

At the time I had kept complete records over an eight-year period and found that my mileage was at least as good as the EPA rating, even though I did far less highway driving than the 45% standard. I ended up giving a brief interview on a later program.

That was a long time ago, and since then the EPA has adjusted their ratings in response to public pressure. But the distress continues.

This Edmunds post asks: “So why doesn't your fuel economy match the EPA rating?” It explains that since those changes, applied to the 2008 model year, “ratings aren't really all that far off the real-world mpg that consumers get….While there are lots of people who cannot under any circumstances get their vehicles to come close to the official ratings, there are also lots who regularly meet or exceed them.” The only exceptions were some poorly run tests by Ford, Mercedes-Benz and Hyundai-Kia that resulted in government-ordered adjustments to the ratings and fines to the companies. (The companies rather than the EPA do their own tests and submit the results.)

So if it was possible to match the standards before 2008, and since then there are “lots of people who regularly meet or exceed them," why is it still an issue? Other factors like weather, terrain and congestion do come into play, but Edmunds explains, “calm drivers, those motorists who don't accelerate constantly and who avoid unnecessary lane changes, get 35 percent better fuel economy than other drivers.”

My idea of the third option expands on that definition of calm drivers. I can tell just by watching brake lights of cars ahead of me and the drivers who pass me on the way to a red light that many drivers seem to think they have only two choices with their right foot: keep it on the accelerator or press on the brake. As a result they try to drive the speed limit as close to the intersection as possible before braking to a stop.

The third option is to simply lift your foot when approaching a red light or approaching a vehicle that is already braking. This allows your car to slow down gently (and likely causes the person following too close behind you to apply the brake.) It only requires someone to look ahead while driving to anticipate problems. That person following too close does not have the time to anticipate and is forced to react immediately to any speed variation of the car in front. This is easy to observe on any road or highway in the country as the brake lights flash on and off.

The physics is simple. It takes fuel to accelerate and maintain speed. Each time the brake is applied it undoes some of that work. In effect some gasoline has been used to produce heat cause by friction at the brakes instead of producing motion. It’s pure waste. Critical thinkers hate waste.

Doing the Math

Often the people who give us information are counting on us not to think too hard about it.  They especially count on us not to do the math.  It’s a reasonable expectation on their part because many people are intimidated by anything mathematical and avoid it whenever they can.  But it doesn’t have to be that way and we will make better decisions when aided by some simple calculations.

What brought this to mind was an ad for a railroad saying that they move a ton of freight 450 miles on a single gallon of fuel.  True, railroads are very efficient, but most people hearing this would automatically compare it to auto gas mileage.  You can’t move a ton of freight in your car that gets 25 or 30 miles per gallon.  If you have a truck that can carry a ton of freight it might get only 18 mpg or less.  That’s less than 1/20 of the railroad efficiency.  But that is the comparison they want you to make.  Their real competition, an over-the-road tractor-trailer can carry a 40,000-pound load.  That’s 20 tons.  According to Popular Mechanics:  “New fuel-economy standards that take effect beginning in 2014 will require semi trucks with a sleeper cab to get 7.2 mpg on level roads.”  Using simple math, 7.2 times 20 = 144 or just about 1/3 of the railroad number.  Our new conclusion is that railroads are indeed more efficient, but not by the huge amount we were led to believe (and trucks are often easier to unload).

Another tricky area is percent calculations.  If the stock market goes down by 20%, then goes back up by 20% is does not end up where it started.  Think about it using 100 as the starting point.  If it goes down by 20%, it’s at 80.  Now 20% of 80 is only 16, so a 20% rise leaves it at 96 (not 100).  Likewise when a store runs a discount of an additional 20% off, here’s how it works.  If the original price was $100 and it was reduced by 30%, it now sells at $70.  An additional 20% off is $70 minus $14 (20% of 70 = 14).  The new sale price is now $56.  You can’t take the 20% plus 30% and expect to get it at half price, or $50.  It seems tricky and a little deceptive, but it’s fairly easy when you think it through.

Look closely at news stories reporting percent changes in defects.  One might feature scary headlines saying that the percentage of school buses failing inspection jumped by 50%.  Buried in the article are the numbers.  Did it jump from 4 to 6, or from 50 to 75?  Both are a 50% increase.  What you may never see in the article is the total population.  Are they talking about 10 or 100 or 10,000 buses?  This makes a big difference, but the headline is designed to catch your eye and elicit concern.

Finally, consider how the government, advertisers and advocacy groups describe savings, spending and crises by manipulating time frames.  Instead of $200 billion per year, we hear $2 trillion over the next 10 years.  Auto loan companies lower payments by increasing the term of the loan (but you will ultimately pay more interest).  We hear about certain diseases killing or affecting one person every 6 minutes instead of a total of 87,600 people (less than .03 percent of the population).  The time frame is manipulated to manipulate your reaction to it.

Sometimes doing the math and paying attention to details can make a big difference in your reactions to numbers.  It may even tell you how realistic the numbers are in the first place.  It pays to be careful.