It sounds like you're referring to the "bump and glide" technique the
Prius hackers rave about. I am not wholly convinced it is indeed for
real but keep an open mind. However, assuming it is, it's due to a
quirk in the way their ICE works.
For an EV, the vehicle needs X kwh/mi to counter aero and wheel drag to
maintain a certain speed. Allowing it to coast down, then speed up,
should not have any efficiency gain. This means half the time the motor
puts out 0 KW and the other half 2*X KW. Unless you put it in neutral,
the tranny and motor turning losses still apply.
Motor losses typically are not linear so running it at twice the power
for half the time is worse off efficiency wise. The only possible
savings are in disconnecting the transmission by putting it in Neutral.
Danny
robert mat wrote:
>This post could be better titled, perhaps as: HOW TO DRIVE AN EV FOR MAXIMUM
RANGE.
>
>If you've been watching an ammeter carefully, you can see how its possible to
reduce amps by ~80% at little cost in speed, by coasting, once the EV has gone
up to speed (assuming no regen brakes. My motor is an Advanced 9 inch.)
>
>Its a sobering lesson for gasoline drivers: Seems that driving in the "normal"
way is burning up gasoline needlessly. Is there a way to have an ammeter-like
gauge for gasoline cars?
>
>Rob Matthies
>
>
>
>
>
>
>
>bruce parmenter <
ev_list_editor@...> wrote: EVLN(Tofu maker Toya pulses &
glides his hybrid to nenpimania)
>[The Internet Electric Vehicle List News. For Public EV
>informational purposes. Contact publication for reprint rights.]
>--- {EVangel}
>
http://www.iht.com/articles/2007/04/05/business/sxhybrid.php
>Mileage maniacs push limits of hybrids
>By Terje Langeland Bloomberg News April 5, 2007
>
>TOKYO: Toyota Motor says its Prius gasoline-electric hybrid car
>can get about 55 miles to the gallon, making it one of the most
>fuel-efficient cars on the road. That is not good enough for
>Takashi Toya.
>
>Toya, a 56-year-old manager for a tofu maker in central Japan,
>puts special tires on his Prius, tapes plastic and cardboard over
>the engine and blocks the grill with foam rubber. He drives
>without shoes and hacks into his car's computer - all in the
>pursuit of maximum distance with minimum gasoline.
>
>Toya is one of about 100 nenpimania, Japanese for "mileage
>maniacs," or hybrid owners who compete against each other to
>squeeze as much as 115 miles per gallon out of their cars. In a
>country where gasoline costs more than $4 a gallon, at least $1
>more than the average U.S. price, enthusiasts tweak their cars
>and hone driving techniques to cut fuel bills and gain bragging
>rights.
>
>"My wife thinks I've joined some strange secret society," Toya
>said last January at a nenpimania gathering in Nagoya in central
>Japan.
>
>Mileage maniacs are not alone in pushing the limits of hybrid
>vehicles. As the U.S. automakers General Motors and Ford Motor
>race to introduce their own models, first rolled out by Japanese
>companies in 1997, engineers at Toyota and Honda Motor are trying
>to increase hybrid performance to maintain their advantage.
>[...]
>Hybrids combine a conventional gasoline engine with an electric
>motor. The electric motor powers the vehicle at low speeds, and
>the gasoline engine kicks in as the car accelerates. The motor
>uses the motion of the wheels to recharge the batteries.
>[...]
>While the nenpimania may take things to extremes, there is a long
>history of car owners tinkering with their machines to improve
>gas mileage.
>
>"The Gas Mileage Bible" (Infinity Publishing, 2006) promises to
>help drivers improve fuel efficiency by more than 30 percent. It
>is the latest in a line of books stretching back to at least
>1942, when an American author named Lee Richter published a
>64-page pamphlet on increasing tire and gas mileage to help save
>resources for the U.S. war effort.
>
>Since the 1997 release of the Prius, the first mass-market
>hybrid, owners in Japan and elsewhere have fiddled with their
>cars to raise mileage and shared tips, including the best driving
>techniques, over the Internet. The mileage maniacs strive to
>perfect what they call the "pulse and glide" driving method.
>
>On a chilly Saturday afternoon in Aichi Prefecture, a short drive
>from Toyota's world headquarters in Toyota City, Toya removes his
>right shoe to demonstrate. Pulsing and gliding demands
>sensitivity when pushing or releasing the accelerator, so only
>his big toe touches the pedal.
>
>Toya accelerates, or pulses, to 29 mph, then glides down to 25
>mph before pulsing again. The car uses no fuel when gliding.
>
>While driving, Toya monitors three pocket-sized electronic
>gadgets designed by Yoshiyuki Mimura, a fellow hybrid enthusiast.
>The dashboard devices use the car's computer to display engine
>rotation speed, coolant temperature, accelerator position, brake
>pressure and battery charge.
>[...]
>"We listen to our customers' opinions and accept them as
>materials for product development," a Toyota spokeswoman, Shiori
>Hashimoto, said in response to questions about the mileage
>maniacs.
>
>Toyota and other Japanese automakers are focusing on improving
>hybrid batteries and making the vehicles cheaper, Endo said. The
>cars now cost about �600,000, or $5,100, more than the equivalent
>conventional vehicles.
>
>Toyota plans to introduce a new Prius by 2009 that will be
>smaller and cheaper, Endo said. The mileage maniacs say they look
>forward to the challenge of improving its fuel efficiency.
>
>"The vehicle will be high-tech," said the enthusiast, Mimura. "I
>think it'll be more difficult to hack."
>
>Copyright � 2007 the International Herald Tribune All rights
>reserved
>-
>
>
>
>
>Bruce {EVangel} Parmenter
>
>' ____
>~/__|o\__
>'@----- @'---(=
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