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EPA Fuel Economy Myth: Too High, Too Low?
ThosLives asks: "I have seen here on Slashdot , and just about every other publication, numerous articles about fuel cells, hybrid vehicles, and the inaccuracies of EPA fuel economy stickers. For instance, today there is a review of the Toyota Prius that had the famous line 'Since no car really achieves the EPA estimated mileage...' I happen to drive a car with an EPA sticker of 21 city 25 highway (all figures in miles per gallon). I've driven the car for 47000 miles and the lowest I've ever seen is 23 and some change; the highest, 36.3 (I'm probably about 60% highway 40% stop-and-go and yes, the high was on a long highway trip). My all-time average is about 28.5. As most people get less than the EPA mileage, how does the Slashdot readership fare when it comes to EPA sticker vs actual experience, and on what type of vehicle?"
"Am I a rare breed that can drive my car (2.0L I4, 170 HP, 6-speed manual) aggressively (I've had coworkers and friends say 'woah!' more than I'd like to admit *grin*) and still stomp the EPA sticker? Did I get lucky with a phenomenal car? Am I enough of a counter-example to thwart the belief that the EPA figures are 'too liberal'? Are fuel economy issues just FUD from [insert lobby group of choice]? Or is the answer simply 'it depends on how you drive, what you had for breakfast, and the color of your neighbors' cat?'"
Your mileage may vary.
My mileage dropped drastically after pieces of the neighbors' cat got caught in the air intake.
If it hadn't been a black cat I wouldn't have run over it at night.
So, yes, mileage depends on the cat's color.
Show me on the doll where his noodly appendage touched you.
When the weather is warm, and that seems to be the biggest factor, I get the EPA-rated 70 mpg or more in my 2000 Honda Insight. 55 on cold winter days.
Driving at moderate speeds is also a big factor.
The whole system should be dumped in favor of vehicle choice, not artificial limits put on cars by the government.
The truck exemptions (that allow for SUVs to have pretty much any fuel economy [or lack there of]) came from the late 1970s when most trucks were used by farmer and construction workers. The idea was to help those people, who generally are involved in small business and make peanuts anyway.
Times have changed, now everybody and his brother has an SUV or pickup truck (even if they don't admit it). The regulations haven't changed, not because of a scam, but because the federal beaurocracy is a mess. Sure, the oil-loving administration isn't going to hurry along any changes, but they aren't doing anything actively to prevent such changes either.
My '03 Hybrid Civic had (I think) 48/47 on the sticker. When I drive it, the "MPG" meter in the dashboard ends up around 42-46. At the pump, I actually get 39-44.
-- I prefer the term "karma escort."
You Americans could learn a lot from the rest of the world when it comes to getting more MPGs.
:-)
Just do what we do -- use a bigger gallon!
Low-tech solutions to hi-tech problems
I drive a 2000 Jetta TDI, and I am no light foot with it. The EPA rating for the car is 42/48 and my personal lifetime average for the car is currently at 47.1 MPG. On longer trips of predominately highway i have had mileage about around 52-53 miles per gallon, this is with cruising at 70 mph. Got to love driving a diesel car :)
Higher compression engines, or more highly-tuned engines, need higher octane gas. Mostly, it's to prevent knocking (early detonation caused by compression rather than spark). Any good car of relatively recent make (at least the past 10 years, if not older) will have a knock sensor to adjust for lower-octane gas, at the expense of fuel usage. However, if your car is designed to run on 87 octane, higher test gas shouldn't make much of a difference.
Actually, there is less energy potential per gallon in higher octane gas than lower. That's not really an issue, though. What most likely happened was that previously you were not using the proper octane-level gas for your engine's compression and the ECM was adjusting to a less optimal program to compensate. As a side note, race gas and airplane gas have much higher octane ratings due to the use of lead additives. Don't try this in your car. Lead will kill your cats in a matter of minutes, not days or months. Race cars and airplanes don't have catalytic converters.
First off, most additives are snake oil. Pretty much the only thing that works is Techron (and knock-off brands using a similar formulation). If you fill your car at a station with Techron or a similar cleaning additive, there's no reason why you should have to add injector cleaner on your own. If you must, an application once or twice a year is sufficient. Any more often and you're just throwing money away. As for better gas giving you better mileage, that's true up to a point. As I mentioned already, higher compression engines require higher octane fuels. If you're not using the right fuel, your engine will operate inefficiently. Using a higher octane gas than is required is useless if your car can't adjust its compression ratios to make use of it (ie, putting 92 octane gas in a low compression engine like many American-made engines isn't going to help anything, while putting 87 octane in a high compression Porsche engine is going to give you poor performance and mileage). If it's bad gas you're worried about, the most common problem is too much water in the gasoline. You can solve this problem with an alcohol additive to "dry" the gas. Other problems like too much sulfur (I believe that was the problem recently with some gas down in Florida, among other places) don't have an easy remedy, and all you can do is stop driving, have the car towed, and empty the tank. Run a few tanks of good gas through the engine and it'll be fine.
As others have already stated in this article, there are many other factors to consider. Low tire pressure, dirty air filter, oil, oil filter, bad alignment, too much weight (of the driver, passengers, and any cargo), etc will all have an effect on your mileage. Also, most cars will get their best mileage at low RPMs. If you can cruise at 2000RPM, you're going to get much better mileage than cruising at 5000RPM (just be careful -- you're going to be in a high gear to cruise at such a low RPM, and trying to accelerate in that gear could cause you to lug your engine. This is more important in high-revving, low-torque engines than it is in low-revving, high-torque engines).
Links:
Altough, around 2 months ago I performed a 'test'.
During the whole tank of gas, I accelerated as slow as I could never pressing the gas more than 1/4 of the way. I knew the lighs were going to turn red, so why accelerate? I eased on slowly and came up to the red using as little break as possible (a waste of energy)... maybe even rolling into the light as it would turn green and _then_ slowly accerlerating.
On the highway, I would stay in the right lane (insane for me). The speed limit is 70, but I would hold 63.
For the tank I averaged 35mpg.
Moral of the story. The car you choose does have a lot to do with your final MPG. But your driving habits also have a huge amount to do with your fuel usage.
I get twenty kilometers per litre, that's about fifty miles per gallon, on average, and that's with a very ordinary turbodiesel, nothing fancy or especially fuel economic (and a pretty quick driving style).
However, heavy lobbying (GM, C and Ford) managed to get defense contractors and other contractors, landscapers included in the scheme.
In the late eighties creative accountants started to include ordinary companies like small entrepenurs and got IRS approval for this. When the SUV market exploded in the nineties it became common for everyone with a small company (dentists, doctors etc) to get the tax break.
It's allways possibly to debate what came first; the tax break or the SUV (as an evolution from the truck and the station wagon)?
I think the SUV would have appeared sooner or later as an evoutionary thing within car industry but it would never had gotten so widespread without the tax break. And the truck segment would have been far far smaller than today.
The tax break is a protectionistic piece of shit mutated far from the original concept without any thought of the consequences, be it environmental, energy policy or foreign policy. If someone where to write a book on how special interest is allowed to corrupt US policy on several areas the SUV tax break case is a perfect example.
And BTW to the root poster that brought up this topic: The tax break is far greater than $4000. According to Taxpayers for common sence it's possible get tax break around $100000. They site an example where a business owner can buy a $110000 Hummer and deduct $106000.
Melius mori in libertate quam vivere in servitute.
According to Time Magazine, gasoline accounts for 44% of US oil consumption. Diesel fuel, heating oil account for another 19%. Plastics procution is buried somewhere in the "other products" category, which accounts for only 15%. So while I can't say off hand exactly how much petroleum is used for plastics, I CAN say that at least about three times as much is used for gasoline.
Look, you're right that it's a multifaceted problem. Probably heating and electricity production (in which oil plants play a non-negligable roll) are even bigger concerns than plastic; however, gasoline is the largest single contributor.
More over, gasoline consumption is probably one of the easiest areas in which to make significant improvement. Unless you build your home or make major, costly, renovations, efficient heating and cooling can be fairly difficult. There are some simple things you can do, but you can only make so much headway. Electricity consumption is much the same situation, and effecting how it's produced is a more long term project.
On the other hand, it's quite easy for most people (who don't need to do major hauling for construction or farming) to buy a vehicle with nearly twice the fuel efficiency of many SUVs, so realistically this is the best way to attack the problem in the short term on an individual level. So, to me saying "oh what about plastics and heating, etc." still is a pretty flimsy excuse for making such a wasteful choice."You call it a new way of thinking; I call it regression to ignorance!" -- Operation Ivy