driving technique

My sister has a very interesting driving technique-- she steps on the
gas for a few seconds (3-5s) and then completely lets off the gas for
a few seconds (3-5s). She never uses steady pressure... ever. So
basically, the car is ALWAYS either accelerating or decelerating. It
is highly annoying if you are the passenger, but interestingly enough
she gets about 46 MPG in her 06 HCH - which is very good for Chicago
given our extreme weather and terrible traffic patterns. I am very
careful with my 06 HAH and use the trip computer to guide how I drive.
I try to not accelerate too quickly, and I am very steady. I get about
30-32 MPG in Chicago. The other day, she borrowed my HAH, and I was
VERY surprised to see that she returned it to me with better mileage
that I had. She used it for local trips, and I am sure used her usual
always accelerating or decelerating. It is not really "pulse and
glide" -- she does the "pulse" but there is no glide. Also, her
variation in speed is small - maybe 5-8 miles per hour as opposed to
the typical 10+ of "pulse and glide." Does this make sense to anyone?
Why wouldn't her constant stepping on the gas ruin the mileage? Any
ideas?

john
http://www.zone-car.com

That must annoy drivers behind her in traffic.

What are HCH and HAH?


"john" > wrote in message
ps.com...
> My sister has a very interesting driving technique-- she steps on the
> gas for a few seconds (3-5s) and then completely lets off the gas for
> a few seconds (3-5s). She never uses steady pressure... ever. So
> basically, the car is ALWAYS either accelerating or decelerating. It
> is highly annoying if you are the passenger, but interestingly enough
> she gets about 46 MPG in her 06 HCH - which is very good for Chicago
> given our extreme weather and terrible traffic patterns. I am very
> careful with my 06 HAH and use the trip computer to guide how I drive.
> I try to not accelerate too quickly, and I am very steady. I get about
> 30-32 MPG in Chicago. The other day, she borrowed my HAH, and I was
> VERY surprised to see that she returned it to me with better mileage
> that I had. She used it for local trips, and I am sure used her usual
> always accelerating or decelerating. It is not really "pulse and
> glide" -- she does the "pulse" but there is no glide. Also, her
> variation in speed is small - maybe 5-8 miles per hour as opposed to
> the typical 10+ of "pulse and glide." Does this make sense to anyone?
> Why wouldn't her constant stepping on the gas ruin the mileage? Any
> ideas?
>
> john
> http://www.zone-car.com
>

People that pulse drive like that **** off everyone behind them which
makes them rolling accidents because everyone tries to pass the idiots.
They should be taken off the road.

Sure they might be able to get better mileage, but at what cost? How
many lives are sacrificed and how many vehicles get wrecked for her 10
mpg extra?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Scott Buchanan wrote:
> That must annoy drivers behind her in traffic.
>
> What are HCH and HAH?
>
>
> "john" > wrote in message
> ps.com...
>> My sister has a very interesting driving technique-- she steps on the
>> gas for a few seconds (3-5s) and then completely lets off the gas for
>> a few seconds (3-5s). She never uses steady pressure... ever. So
>> basically, the car is ALWAYS either accelerating or decelerating. It
>> is highly annoying if you are the passenger, but interestingly enough
>> she gets about 46 MPG in her 06 HCH - which is very good for Chicago
>> given our extreme weather and terrible traffic patterns. I am very
>> careful with my 06 HAH and use the trip computer to guide how I drive.
>> I try to not accelerate too quickly, and I am very steady. I get about
>> 30-32 MPG in Chicago. The other day, she borrowed my HAH, and I was
>> VERY surprised to see that she returned it to me with better mileage
>> that I had. She used it for local trips, and I am sure used her usual
>> always accelerating or decelerating. It is not really "pulse and
>> glide" -- she does the "pulse" but there is no glide. Also, her
>> variation in speed is small - maybe 5-8 miles per hour as opposed to
>> the typical 10+ of "pulse and glide." Does this make sense to anyone?
>> Why wouldn't her constant stepping on the gas ruin the mileage? Any
>> ideas?
>>
>> john
>> http://www.zone-car.com
>>
>
>

Mike Romain wrote:

> People that pulse drive like that **** off everyone behind them which
> makes them rolling accidents because everyone tries to pass the idiots.
> They should be taken off the road.
>
> Sure they might be able to get better mileage, but at what cost? How
> many lives are sacrificed and how many vehicles get wrecked for her 10
> mpg extra?

And I don't for an instant believe that most vehicles *will* get better
mileage if driven that way. Manual trannies, maybe, but not automatics.
You'd be perpetually locking and unlocking the torque convertor, never
letting it settle down to its most efficient (locked) condition. The
practice is a stupid waste based on a hunch, not on engineering.

john wrote:
> My sister has a very interesting driving technique-- she steps on the
> gas for a few seconds (3-5s) and then completely lets off the gas for
> a few seconds (3-5s). She never uses steady pressure... ever. So
> basically, the car is ALWAYS either accelerating or decelerating. It
> is highly annoying if you are the passenger, but interestingly enough
> she gets about 46 MPG in her 06 HCH - which is very good for Chicago
> given our extreme weather and terrible traffic patterns. I am very
> careful with my 06 HAH and use the trip computer to guide how I drive.
> I try to not accelerate too quickly, and I am very steady. I get about
> 30-32 MPG in Chicago. The other day, she borrowed my HAH, and I was
> VERY surprised to see that she returned it to me with better mileage
> that I had. She used it for local trips, and I am sure used her usual
> always accelerating or decelerating. It is not really "pulse and
> glide" -- she does the "pulse" but there is no glide. Also, her
> variation in speed is small - maybe 5-8 miles per hour as opposed to
> the typical 10+ of "pulse and glide." Does this make sense to anyone?
> Why wouldn't her constant stepping on the gas ruin the mileage? Any
> ideas?
>
> john
> http://www.zone-car.com
>

An old C&D magazine covered this in better detail than I can, but
basically it comes down to:

Your car engine is most efficient around 80% load and low rpms.
Instead of driving at 20% load and 20% throttle, she's driving at 80%
load and 0% load.

You will get better fuel economy this way, but it's annoying as hell if
your the car behind or a passenger.

She might also drive slower, or is just easier on the gas.

Ray

news wrote:


>
> An old C&D magazine covered this in better detail than I can, but
> basically it comes down to:
>
> Your car engine is most efficient around 80% load and low rpms.
> Instead of driving at 20% load and 20% throttle, she's driving at 80%
> load and 0% load.

But that's such a gross over-simplification that its not even close to
being a real representation of what happens if you try to drive a car
that way. Just off the top of my head:

- Whenever you transition from off-throttle to on-throttle, there's a
big slug of fuel is used as you re-apply load to the engine Carbureted
cars had accelerator pumps, but even modern ECMs have acceleration
enrichment as part of the programming

-timing is retarded during acceleration

- If you have an automagic transmission, the torque convertor unlocks
every time you let off the gas and then has to re-lock after you get
back on the gas, rather than staying locked in a steady-state. On most
cars, it takes a few seconds before the convertor re-locks when you
re-apply the gas after lifting your foot, and energy is wasted during
that time. Not to mention a TON of added wear on the TC lockup clutch!

On Sep 21, 3:22 pm, news > wrote:
> john wrote:
> > My sister has a very interesting driving technique-- she steps on the
> > gas for a few seconds (3-5s) and then completely lets off the gas for
> > a few seconds (3-5s). She never uses steady pressure... ever. So
> > basically, the car is ALWAYS either accelerating or decelerating. It
> > is highly annoying if you are the passenger, but interestingly enough
> > she gets about 46 MPG in her 06 HCH - which is very good for Chicago
> > given our extreme weather and terrible traffic patterns. I am very
> > careful with my 06 HAH and use the trip computer to guide how I drive.
> > I try to not accelerate too quickly, and I am very steady. I get about
> > 30-32 MPG in Chicago. The other day, she borrowed my HAH, and I was
> > VERY surprised to see that she returned it to me with better mileage
> > that I had. She used it for local trips, and I am sure used her usual
> > always accelerating or decelerating. It is not really "pulse and
> > glide" -- she does the "pulse" but there is no glide. Also, her
> > variation in speed is small - maybe 5-8 miles per hour as opposed to
> > the typical 10+ of "pulse and glide." Does this make sense to anyone?
> > Why wouldn't her constant stepping on the gas ruin the mileage? Any
> > ideas?
>
> > john
> >http://www.zone-car.com
> An old C&D magazine covered this in better detail than I can, but
> basically it comes down to:
> Your car engine is most efficient around 80% load and low rpms.
> Instead of driving at 20% load and 20% throttle, she's driving at 80%
> load and 0% load.
> You will get better fuel economy this way, but it's annoying as hell if
> your the car behind or a passenger.
>


I'm really straining my memory banks here, but......
Remember back in the '70s when gas lines were long and every car
commercial bragged about how good their gas mileage was? Well, about
that time there were all these gas mileage contests. You know the ones
were they used a 98 pound driver and a stripped frame with 4 (or maybe
3) wheels on a closed course track. I remember a lot of these contests
where the little vehicle would get 150+ miles per gallon. ANYWAY, the
details are sketchy on all this, but I do remember that a lot of the
vehicles would accelerate and coast, accelerate and coast, unlike the
theory that tells us that they should stay at a steady speed. Of
course these vehicles were impractical on the street, but maybe there
is something to the accelerate and deaccelerate methods.

On Sep 21, 2:34 am, john > wrote:
> My sister has a very interesting driving technique-- she steps on the
> gas for a few seconds (3-5s) and then completely lets off the gas for
> a few seconds (3-5s). She never uses steady pressure... ever. So
> basically, the car is ALWAYS either accelerating or decelerating. It
> is highly annoying if you are the passenger, but interestingly enough
> she gets about 46 MPG in her 06 HCH - which is very good for Chicago
> given our extreme weather and terrible traffic patterns. I am very
> careful with my 06 HAH and use the trip computer to guide how I drive.
> I try to not accelerate too quickly, and I am very steady. I get about
> 30-32 MPG in Chicago. The other day, she borrowed my HAH, and I was
> VERY surprised to see that she returned it to me with better mileage
> that I had. She used it for local trips, and I am sure used her usual
> always accelerating or decelerating. It is not really "pulse and
> glide" -- she does the "pulse" but there is no glide. Also, her
> variation in speed is small - maybe 5-8 miles per hour as opposed to
> the typical 10+ of "pulse and glide." Does this make sense to anyone?
> Why wouldn't her constant stepping on the gas ruin the mileage? Any
> ideas?
>
> johnhttp://www.zone-car.com

I have no idea what a HAH or HCH is. I don't believe that MPG story
for an instant. Ignoring the extra fuel injected to accelerate, the
car is repeatedly overcoming inertia.

On Sep 21, 12:18 pm, Steve > wrote:
> Mike Romain wrote:
> > People that pulse drive like that **** off everyone behind them which
> > makes them rolling accidents because everyone tries to pass the idiots.
> > They should be taken off the road.
>
> > Sure they might be able to get better mileage, but at what cost? How
> > many lives are sacrificed and how many vehicles get wrecked for her 10
> > mpg extra?
>
> And I don't for an instant believe that most vehicles *will* get better
> mileage if driven that way. Manual trannies, maybe, but not automatics.
> You'd be perpetually locking and unlocking the torque convertor, never
> letting it settle down to its most efficient (locked) condition. The
> practice is a stupid waste based on a hunch, not on engineering.

Even for manual trannies it isn't that easy. There is a critical
throttle opening, somewhere around 3/4 that provides best economy, but
it is hard to find, and you must take the car out of gear and coast
down that way (or with clutch in).

Now, there are these special built cars where there is NO throttle and
the car is accelerated to a pre-computed speed, then coast down. But
on these cars the carburetion or injection systems are readjusted for
no power enrichening, or the engine never had that feature in the
first place.

I doubt if her technique really works in practice, in traffic on
normal roads. It can work on a test track IF the person doing the
tuning setup is sharp enough, but they have to know a lot about that
particular engine.

On the other hand, there is ONE truth to this. A frequent admonishion
for good economy is to avoid "jackrabbit" starts. But they neglect to
define what they mean by a jackrabbit start. It does NOT mean to start
off with very little throttle and creep slowly up to cruise speed.
That wastes gas. In stick shift cars best economy is obtained by
accelerating at about 60 to 70 percent throttle, and shifting very
early.

On automatics, that can hold shift points too high, so the value of
optimum throttle opening drops to maybe around 40% or so- depends on
the car. In practice, what this means is accelerate normally. There
are other ways to avoid high gas consumption like driving the speed
limit, avoid tailgating, and look ahead and play traffic lights.
Brakes are the biggest deterrents to gas mileage- avoid using them
except in an emergency.

Proper driving would be to accelerate fairly quickly (no spinning the
wheels, but fairly quickly) to the speed limit and hold it there.
Assuming conditions allow that.
See if she would try that.