Fuelling the Hypermiler Myth

I’ve just read this article on Easy Ways to Save Money on Gas on LifeHacker and towards the end of the article they suggest taking some tips from Hypermilers. The tips were as follows:

  • Use your cruise control. You’ll never be able to maintain a perfect cruising speed as well as the cruise control.
  • Drive the speed limit. Unless you’re driving across the entire country speeding won’t save you more than a few minutes, will cost you more in gas, and increase the chance of being involved in an accident.
  • Stop using your brakes to slow down. If you know your highway exit is a mile away, don’t drive 80 mph until the ramp and slam your brakes to slow down to the 30 mph that will get you safely off the expressway.

I already track my cars gas mileage regularly because it is an easy way to spot small problems with the engine before they become big problems and I know my average is about 28mpg which isn’t bad for a 17 year old sportscar being driven spiritedly. I’m also aware that we need to look after the environment and that we should try and save resources where possible. However, I took umbridge to the points listed above because they are the same bilge reported frequently these days and by dint of some simple research can be easily disproved.

Cruise control is more gas efficient by keeping a steady speed

Now this is almost true on a perfectly flat, perfectly straight road but any driver should be able to keep a steady speed on a perfectly flat, perfectly straight road if they know how to drive. The thing is it doesn’t really save you any gas, because gas consumption is controlled by engine speed, not vehicle speed and therefore to be most economical the car should maintain a constant engine speed and load. On a hilly road the cruise control will frequently increase and decrease the engine speed to maintain that constant vehicle speed using more gas than a driver who keeps their foot balanced and allows the revs to stay constant (balanced with load) and allows for the speed to deviate slightly on the inclines.

Driving the speed limit, or sticking to 55mph saves you gas

The speed limit of 55mph was established across much of the United States during the fuel crisis of the 1970s. At that time this was calculated by the government to be the statistically most economical speed for a statistically average car of that period. Now you may not have noticed but car design and technology has changed a great deal since 1970, and even then there were many different sizes and shapes of car. The most fuel efficient speed for each vehicle is unique and takes into account a wide range of factors like; aerodynamic properties of the vehicle, weight of the vehicle, size of the engine, size of the wheels, ambient air temperature… the list is actually amazingly long. So 55mph was a 1970s average, and the government haven’t recalculated since then. So look at it this way DRIVE THE SPEED LIMIT BECAUSE IT IS THE LAW not for any other fictional reasons. My car has a small turbo charged engine and great aerodynamics, it gives brilliant gas mileage at about 70mph, but I can’t legally drive that fast so I don’t… common sense!

While we’re talking about speed. Speed doesn’t kill, speed does not overly increase the risk of having an accident. The UK Government stated in a report released in September 2006 that;

the proportion of injury crashes involving any speeding vehicle nationally was only 5%

So all those speed cameras, and Speed Kills messages address only 5% of injury causing crashes. Being distracted causes far more accidents, distractions like mobile phones. In the U.S. it is estimated that cell phone distracted drivers are four times more likely to be in a car crash, a Harvard University study states that cell phones cause over 200 deaths and half a million injuries each year on the roads in the U.S., and this number is climbing!

Stop Using Your Brakes to Slow Down

It is true that rapid acceleration has an impact on fuel consumption, and therefore stopping and starting is bad for fuel efficiency. However, your brakes are designed to slow your car down!!! Using the engine and gears to slow the car puts extra load on the engine causing it to burn more fuel. Not only that but slowly letting your speed drift down for the mile or so before your exit off the highway means that the cars behind you have to change their speed and reduce their efficiency for the mile or so you are being smug. It isn’t just your efficiency you should consider, but that of your fellow drivers, so don’t cause additional congestion by crawling down to 30mph just to make your exit without using your brakes. Additionally, if you are exiting from a 55mph road onto a 30mph road, using your brakes and sensible usage of engine and gears to bring the car down to 30mph as you exit doesn’t use any extra fuel since you won’t be accelerating as you merge onto the new road, it also won’t infuriate the drivers around you on the highway or put you at risk of being rammed by somebody doing the speed limit but distracted on their mobile phone!

I know I shouldn’t get so wound up, but hypermilers idiotic suggestions and erratic driving tips just rub me up the wrong way. We need more quality driver education, and the encouragement of better courteous driving skills on our roads. Not dangerous “tips” lacking credible research and evidence.


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