|
|
Your Mileage Will Vary - the Myth and Mystery of EPA Mileage EstimatesSep 27 '05 (Updated Jun 22 '06) Write an essay on this topic.
Popular Products in Cars
The Bottom Line There's a good reason why you can't seem to get the EPA mileage estimate on your car: most of them are wrong.
I've been hearing howls of protest from the owners of hybrid cars. They were certain that they'd be getting upwards of sixty MPG in their new cars, and now they're mad as hell that they rarely (if ever) come within ten MPG of that magic number. Of course, there are probably some owners of full-size pickups and SUVs who would give their first-born child to get fifty MPG, but hey - they could have bought a smaller car if they'd really wanted to. It's not, however, only drivers of hybrids who are finding that they can never seem to reach that EPA mileage estimate pasted on the window of every car, truck, and SUV in the dealer showroom - it's just about everybody. And these days with gasoline prices hovering around the three-dollar per gallon mark in much of the US, a lot of people have suddenly become extremely interested in attaining or even bettering the fuel economy they believed was within their grasp. So why is it that your mileage varies? Before we go any further, let's make certain that we're comparing apples to apples: are you calculating your gas mileage correctly? Gas mileage is the number of miles driven between fill-ups divided by the number of gallons consumed*. There: now that we know we're calculating fuel economy using the same formula as the EPA, let's talk about why your results are different. They're different for two reasons, and one of them is probably your fault. You drive like a maniac, weaving through traffic at twenty MPH over the speed limit, roar away from stop lights like a jackrabbit on steroids, and sit in the parking lot of the grocery with the engine idling while you wait for the spouse to run in for a gallon of milk and pack of Marlboros. You carry around a trunk full of sand bags all year long. You haven't tuned up your car since the Clinton administration; haven't checked the air in your tires since Newt Gingrich was Speaker of the House. Here are some thoughts for you to ponder: • On the average, every 100 pounds of extra weight in your car decreases gas mileage by one MPG (so you could toss your brother-in-law and realize a 3MPG increase?) • If your tires are under-inflated by five PSI, you're cutting mileage by as much as four per cent - keep them inflated to the proper values, and save on tire wear as well (the proper values are printed on a sticker on the door pillar or the glove box door). • An ill-tuned engine with dirty air and fuel filters can cost you 10% of your mileage. Spending a few bucks can save a lot of bucks (see pvreditor's expansion on this idea here.) • Excessive speed, even in your highest gear, increases fuel consumption by anywhere from 5% to 25% even if you're only 5MPH over the speed limit. Slow down! Not only do you save on fuel, speeding contributes to more auto accidents every year than does DUI. • Idling uses about two gallons of gas per hour. Most cars need less gasoline to restart than they'd consume in thirty seconds of idling. You really want to save? Stop using drive-through windows: park the car and walk inside that bank, restaurant, drug store, coffee shop, liquor store. Look at it this way: you probably don't have to talk to a clown inside... • If you don't drive at all, you don't use any gasoline. Walk. Ride a bike. Ride public transportation (OK, that uses a little gasoline). Your wallet - and your heart - will thank you. So, you say you're already doing all those things and you still can't touch the EPA mileage estimates? Well, that's not your fault, and there's more and more evidence that you're not alone. The well-known magazine Consumer Reports recently (September, 2005) published an article lambasting the EPA and the auto industry for inaccuracies in EPA mileage estimates. This follows on the heels of a press release from the American Automobile Association in March, 2005, making the same claims - and the inaccuracy of the EPA esitmates has been an ill-kept secret for decades. According to CR and AAA, as many as 90% of EPA mileage values are artificially high, in some cases by as much as 35%. There are lots of reasons for these discrepancies, but here are some of the chief reasons: • Auto makers test the cars themselves and report the numbers to the EPA, often using a hand-built prototype instead of the less-efficient production model you or I might buy. • Test cars are not driven outside on the streets for EPA testing. So that tests are standardized regardless of the vehicle, all cars are tested under laboratory conditions on a dynamometer. It's a simulation: No rain, no wind, not a single ditz on a cell phone straddling the lane markers. And the EPA test wildly underestimates the amount of time a car spends idling at stoplights. Don't laugh - you use about 2 gallons/hour while idling (and you don't move an inch). • EPA highway estimates are based on an average highway speed of 48 MPH, which estimate was made in 1975 when the national speed limit was only 55 MPH. Today, cars traveling at the posted speed limit of 65-70MPH on interstates are routinely passed by everything except MoPeds, antiques, and school buses with psychedelic paint jobs. • The EPA combined numbers represent 55% city and 45% highway driving, which is at odds with the average mix of driving reported by AAA - they peg the city:highway ratio at 62:38%. • Some of the worst discrepancies are for hybrids, with CR's road tests coming in as much as 19 MPG below EPA estimates. Dealers know this, but one point of which those livid hybrid aren't aware is that it's a violation of federal law for a company to tell a prospective buyer that the EPA estimates are wrong - and that includes warning buyers that they're too high. The US public has been misled (some might say "shafted") by the EPA test results, which have been criticized by the GAO (Government Accounting Office) for more than two decades. In 1984, EPA began using "corrected" estimates, which are the test results reduced by from 10% to 22% (and still overly optimistic). The EPA continues dragging its feet, perhaps under heavy lobbying from the automotive industry, but is "studying" changing the test and calculation procedures beginning in 2007. What do the bogus EPA mileage estimates mean? For buyers, it means that you can't necessarily trust those EPA mileage stickers if you're trying to compare two vehicles. You'll have to do your own research - it's not just the "ultraliberal" CR that reports mileages that are different from the EPA estimates. Check Road and Track, Car and Driver, edmunds.com, and other enthusiast publications and automotive sites for commercial reviews that include mileage estimates. Here at epinions.com you can find real-world numbers from both owners and renters. Another, more insidious effect of the overly optimistic mileage estimates is that auto manufacturers - whose output must meet Congressionally-mandated CAFE standards (Corporate Average Fuel Economy) - are laughing up their sleeves. Not only are they using incorrect data to make their calculations, they're allowed to use the "pre-correction" EPA estimates: the raw numbers before the 10% to 22% reduction that was instituted in 1984 is taken. Consumer Reports calculates that the true fleet averages - mandated at 27.5 for passenger cars and 20.7 for light trucks - are far below the standards. Their results indicate that fleet averages for passenger cars are approximately 22.7 MPG for cars and 16 MPG for trucks. And the current administration thinks a six-month supply of oil in ANWR will solve our dependence on foreign oil? For your reading information: The Consumer Reports article: http://www.consumerreports.org/main/content/display_report.jsp?FOLDER%3C%3Efolder_id=772749&ASSORTMENT%3C%3East_id=389451&bmUID=1127824630492 AAA's press release as reported by MSNBC: http://www.msnbc.msn.com/id/7128017 A New York Times article: http://www.journalnow.com/servlet/Satellite?pagename=WSJ%2FMGArticle%2FWSJ_BasicArticle&c=MGArticle&cid=1031782188879&path=!nationworld&s=1037645509161 Or enter epa mileage estimate wrong in your search engine of choice * See these instructions if you're not certain that you're doing the calculations correctly - it could take a load off your mind... or maybe make things even worse.  |
| Read all comments (9)|Write your own comment |
|
