<_< Hi Folks,
I was crusing on AOL and ran across this article. For the benefit of those who are unable to access it, I have copied and pasted it below:
Your Mileage May Vary
Government to 'Adjust' Its Fuel Economy Estimates in '08
By ERIC PETERS
"Your mileage may vary" is the government's way of tacitly admitting the fuel economy figures it publishes on new car window stickers may not reflect the actual miles per gallon your vehicle will deliver once it’s in your hands.
The figures are, at best, a rough guide -- not a definitive statement -- based on averages obtained during controlled testing. And as many of us have discovered, the government's estimates are often a tad on the optimistic side.
The reason for the disparity between what the government thinks we might get and what we actually get is pretty straightforward: The way we drive our vehicles is often very different from the way government testers do. We cruise at 70-75 mph on the Interstate instead of 55 mph -- knocking down our potential "highway" fuel economy by as much as 5-10 percent. Or our typical "city" driving consists mostly of fairly abrupt (and very inefficient) 0-20 mph stop-and-go driving instead of steady-state 30-40 mph -- likewise reducing real-world "city" mileage by a significant margin.
The current testing procedures used to estimate fuel economy date back several decades -- and haven't been updated to reflect changing driving habits and traffic patterns.
For example, highway speed limits have gone up by 10-15 mph (or more) in many states, following the 1995 repeal of the 55 mph National Maximum Speed Limit (NMSL). These higher speeds have a (negative) effect on real-world highway fuel economy -- but the current tests assume we still live in a "drive 55" world. Similarly, congestion has worsened markedly in and around most major urban/suburban areas -- increasing the time we spend accelerating and decelerating (which wastes energy and thus fuel).
Finally, the tests currently used are skewed because they assume "optimum" conditions -- even temperatures, intermittent use of power-drawing accessories such as air conditioning -- and so on. But cars burn more gas during "cold starts" on harsh winter mornings than they do at room temperature -- and constant cycling of the AC on a 100 degree July afternoon will likewise cut into the "best possible" mileage you might otherwise get.
But new tests slated to go into effect beginning with model year 2008 vehicles should give consumers a substantially more accurate window into how much gas their new car or truck will use in real-world driving -- because the revised numbers will be based on more realistic driving patterns, including higher speed/higher load driving and more frequent use of power-using accessories such as air conditioning.
The expected result of the changes in testing methods will be an "on-paper" drop in fuel economy of as much as 10-15 percent relative to currently published figures -- but this won’t reflect any actual drop in efficiency (all else being equal).
There'll just be more truth in advertising.
For example, under current tests, an '05 Chevy Silverado is rated at 17.8 mpg in city driving. Under the proposed revised testing system, the same vehicle's published city mileage would fall to 13.9 mpg -- which is probably a lot more in line with what the typical owner is getting. The Toyota Camry's projected city mileage would likewise drop from the current 28.5 mpg to a more realistic 24.2 mpg.
One class of vehicles expected to take a major hit is hybrids -- whose "best case" fuel efficiency often founders on the shoals of real-world driving. The city rating of the Honda Civic hybrid, for instance, would drop some 12 mpg -- from the current 48.8 mpg to a much-less-spectacular 36 mpg. This will be a revelation (and reality check) for many people -- who drive their hybrids outside the envelope of the hybrid's optimal operating range.
This isn't to say it's impossible to realize the best-case mileage your vehicle is theoretically capable of. If you drive very moderately (no rapid acceleration; no high-speed driving) under ideal conditions (no sub-zero cold starts, etc.) you might equal (or even beat) the government's currently published guidelines.
But since few of us drive that way in the real world, it's probably a good thing the government is changing the way it does its testing. Better to know what we're likely to get rather than what we might get -- right?
by Eric Peters AOL Automotive News
Once I finished reading this all I could think was "well, here we go again". If you attended the recent OC Prius Club meeting you heard Dave Hermance discuss the proposed changes to the window sticker information currently available. He strongly urged us to read and review the suggested changes in format and weigh in on them during the current discussion period.
One thing that the above reporter has missed (as usual) is that even with the downward adjustment of the numbers, our hybrids still far outstrip most other vehicles on the road. Also, even with the adjustment, the Prius would still meet the benchmark for the current regulation that allows us the carpool benefit here in California, that of 45MPG, since even with the adjustment in the numbers we would still come out at 48MPG City. I don't remember the exact math he illustrated, but I do remember the number.
Also, another thing he pointed out (and this is really most important for our California owners) is that the carpool benefit is a "pilot" program and that we should be lobbying NOW for this to be extended beyond the scheduled 2008 cutoff date. I think it is quite right to assume that the possibility of this benefit's impact on traffic patterns having been fully studied and accurate conclusions drawn within the current time frame are probably slim and none. If we don't start pushing for the extension (at the very least) and permanent adoption of this plan now we may very well find ourselves shut out in a year.
Take care all and have a super day,
Tisza
Your Mileage May Vary - Bad News for Hybrids
Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by Widdletink, Mar 8, 2006.
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Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by Widdletink, Mar 8, 2006.
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