Date: Fri, 27 Jun 2008 22:06:31 -0500
Reply-To: joel walker <uncajoel@BELLSOUTH.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: joel walker <uncajoel@BELLSOUTH.NET>
Subject: Re: gas prices and fuel economy ... another slant :)
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seeing as how this is Frydaye, i ran across this in the current issue
of Road & Track, and thought it might be appropriate to some
discussions recently on the list ..
Saving Fuel - and still having fun.
Fuel as liquid entertainment
and a search for frog hairs
Road & Track magazine, August 2008
by Dennis Simanaitis
Maybe you're not about to buy a new car, so
"The Fast and the Frugal," elsewhere in this
issue, is good reading but not saving you anything.
On the other hand, you're web-savvy, so you can
wire into roadandtrack.com, search on Bright Green:
Fuels and check out "Your Mileage May Differ,"
May 2006. In fact, with gasoline prices soaring,
this information is golden and worth summarizing
here. Plus, I've learned a thing or two over the
past couple of years.
The Obvious Stuff
I called it obvious back then, but it's still
absolutely crucial. For instance, a 3-psi deficit
in tire pressure translates into a 2-percent hit
in fuel economy. Real-time monitoring helps, but
an old-fashioned (and accurate) tire-pressure gauge
applied regularly rewards you in money, tire tread
and your car's handling as well. Set tires to your
automaker's recommended pressures; if there's a
(somewhat higher) sport setting, all the better.
(But don't OVERinflate - and keep reading to see
why.)
Another suggestion: Keep golf clubs, curling gear
and especially skis at home until your destination
is gold-, curling- or ski-oriented. Loaded ski
racks are a double-hit as they affect frontal area
AND Cd (coefficient of drag).
Don't believe the folk legend that windows-down
aero drag is worse than air conditioning. A/C
can be as much as a 20-percent hit in fuel consumption.
Use it whenever you need to, but not without thought.
Revs - and road speed - aren't free. Apply these with
wisdom as well. That is, canyon-strafing is liquid
entertainment and, to me, well worth the mpg hit. But
revving thoughtlessly on my way home after work is just
wasteful.
In routine acceleration, a fairly heavy foot and short
shifting reduce pumping and throttling losses. Given that
traffic allows it, this can save as much as 20 percent
in city/suburban driving. Plus, it's fun to practice.
A little bit of planning saves fuel. For instance,
companies like FedEx, UPS and DHL know that right turns
are more fuel-efficient than lefts. The "chaining" of
trips, linking errands and other driving activities, is
a particularly good idea.
Two words on fuel-saving gizmos: Forget them.
Some seem to be examples of the Hollywood Producer Rule:
"if one elephant is good, then a hundred elephants must
be better." As you might imagine, this is not necessarily
so. Also, the Federal Trade Commission shares excellent
information at
www.ftc.gov/bcp/edu/pubs/consumer/alerts/alt064.shtm .
In particular, it cites Environmental Protection Agency
findings on such gizmos.
My own modest view: If a gadget were cost-effective,
an automaker would adopt it in a minute and advertize it
like crazy. And, to reiterate, "Your Milage May Differ"
gives full details on these and related matters.
What About "Hyper-Miling"?
"Hyper-miling" has evolved as a sub-genre of automotive
enthusiasm striving to post the highest mpg for whatever
you happen to drive. Its techniques are fun to discuss,
often entertaining to practice, but also demanding of
some plain ol' common sense. Among hot tips are shutting
down the engine at appropriate opportunities; run up and
coasting; running really high tire pressures, refueling
in a most efficient manner and even attempting to exploit
an aerodynamic tug from other traffic.
To take this last one first, drafting an 18-wheeler is
stupid. Yes, in theory you can outbrake him, but not
necessarily in practice -- and the laws of physics are
unforgiving.
Inflating tires beyond the automaker's recommendation will
lower their rolling resistance. But an overinflated tire
has a smaller contact patch that degrades your car's
handling and braking. It'll compromise comfort and wear
as well. By the way, that "51-psi maximum" embossed on the
sidewall is a tiremaker's upper limit based on structural
integrity; it has nothing to do with grip optimization.
Coasting out of gear can appear frugal, but "it ain't
necessarily so." An idling engine requires a dollop of
fuel to keep running; one coming down in gear may well
have a fuel-shutoff. In two words, it depends.
Turning off the engine while coasting is really dim-witted.
Power assist for brakes and steering go away, the latter,
remarkably quickly. If you're really inept, your key-off
might even invoke the steering-wheel lock. And the
subsequent key-on puts the engine into its less-than-fuel-
efficient start-up mode.
By contrast, coasting in gear, and doing anything else to
maintain momentum, is a free ride - and good fun as well.
I especially like downhill sweepers where, traffic permitting,
I imagine I'm piloting a bobsled and steering the path that
scrubs off the least speed.
What about Do-It-Yourself stationary start/stops? This
strategy has its tradeoffs. Hybrids and other dedicated
start/stop systems have high-energy starters and an
optimized restart routine. The DIY variety encounters
start-up enrichment that may well cancel out any benefit.
Caught at a train crossing or in a lengthy tie-up? Sure;
shut it down. But at most traffic lights or in ordinary
stop-and-go traffic, it's likely more efficient to wait
at patient idle (you and the car).
In Search of Frog Hairs
Back in the old Mobilgas Economy Runs, engineers used to
search for what they called "frog hairs," seemingly
insignificant little bits of advantage that might add up
to something measurable.
This search continues today in things like "filling your
tank in the cool of morning so it'll get the most dense
fuel" or "pumping slowly to minimize the production of
vapors" or "keeping your tank near full to minimize its
vapor production." Like other hyper-milling strategies,
each of these has some validity. But how measurable?
And what's the tradeoff of time or convenience?
On the other hand, maybe the frog hair search itself is
its own reward. If it saves a few cents, all the better.
Fuel-Efficient Oils
Automakers are already onto lubricants of lower viscosity,
that is, thinner and easier-flowing oils for enhanced mpg.
Hyper-milers use these oils, typically replenished to
only the lower tick mark of the dipstick, thus minimizing
the volume of oil being pumped around. (A questionable
frog hair: I'd suspect this short fill would have
trade-offs in startup wear and engine longevity.)
By way of background, an oil's SAE grade is a combination
of two numbers; the lower one describing its cold-temperature
viscosity; the higher, its viscosity at elevated temperature.
A 5W-30, for instance, displays 5-weight viscosity (and easy'
flowing in cold start) at sub-zero temperatures, yet it
provides 30-weight viscosity (and hot-running protection)
at 100 degrees Celsius/212 degrees Fahrenheit.
Lubricant suppliers have extended the range of these products.
Mobil 1 Advanced Fuel Economy oil, for example, is a premium
synthetic available in two grades, 0W-20 and 0W-30. These
are claimed to offer as much as a 2-percent benefit in fuel
economy, as measured against comparable 5W-30 and 10W-30
engine oils. By the way, 0W-40 Mobil 1 is already the
original-equipment fill in a good number of cars, Porsche
among them. Having lower viscosity at high temperature,
a 0W-20 or 0W-30 would potentially offer even better
fuel-economy benefits than a 0W-40.
According to Mobil, these new oils meet or exceed warranty
requirements of many cars from Chrysler, Ford, GM, Honda,
Mazda, Toyota and other automakers. The 0W-20 grade is
recommended in 5W-20 applications. In a sense, each offers
enhanced benefits in startup with no sacrifice of protection
once underway.
By the way, Mobile specialists dispel something of a folk
legend the notion that modern engines profit from a non-
synthetic "break-in" oil. This is corroborated by the
many original-equipment Mobil 1 adoptions among automakers.
Some applications (turbocharged, for example) have adopted
a synthetic for its exemplary performance at high temperature.
Others exploit its long-term stability in extending oil-change
intervals to 15,000 miles. And adoptions of Energy
Conserving oils are evidently in the interest of higher mpg.
It can be noted, by the way, that one advantage of a
synthetic base stock is its requiring less viscosity-index
improver than what's needed with a conventional petroleum
stock to achieve the same "crossgrade" characteristics.
One last comment on synthetics: They're premium products
with a premium price. That is, their use may or may not
pencil out advantageously compared with less pricey
petroleum counterparts. Nevertheless, I consider their
other advantage - and the relative cost of a periodic
oil change - as good insurance for my automotive investment.
I'll accept the claimed 2-percent gain in fuel economy
as a welcomed frog hair.
Oil Factoids
Oils are assigned Service Rating by the American Petroleum
Institute based on a series of tests and identified as
part of the "donut" of information on the container.
However, the latest API Rating, SN, has perhaps been the
cause of some misunderstanding. Specifically, this
concerns an oil's antiwear additive, typically ZDDP,
zinc dialkyldithiophosphate. The lighter SNs, 30-weights
and thinner, are low-phosphorous oils formulated to
promote long-term durability of converter catalysts,
the assumption being that a reduced level of ZDDP is
acceptable with metallurgy of today's engines.
Note, though, that heavier SNs, those of 40-weight and
beyond, are not subject to this phosphorous limit.
These oils are seen as appropriate for engines calling
for higher viscosity (and perhaps profiting from a
traditional level of antiwear additive).
Another interesting factoid concerns "green" motor oils,
those said to be formulated from bio-degradable stocks.
In particular, there's a false impression that such
oils can readily be tossed out at oil-change time.
However, two questions arise: The base stock may be
bio-degradable, but what about the additive package?
And much worse, though the original stock may be
environmentally friendly, it's certain that the used
oil will be contaminated with combustion byproducts,
trace metallics and God knows what else. Its disposal
requires the same care as that of conventional
"non-green" used oils.
Furthermore ...
As you may recall, EPA Mileage Ratings now incorporate
additional tests more accurately reflecting our actual
driving patterns. Speeds are higher, cold start is
evaluated in one, air conditioning gets used in another.
The resulting EPA Combined Mpg figures, with 55/45
City/Highway weighting, come rather closer to our real
world than their pre-2008 analogues.
Am I the only one bothered by car advertising that cites
ONLY the EPA Highway number?
I thought so. Let's all be better informed through
EPA's www.fueleconomy.gov/. And good luck with your
own personal quest for frog hairs.
