[LittleLamb]

Coast and glide saves everybody gas, doesn't it? My dad, a real penny pincher, taught me to take my foot off the gas when approaching stop signs, and if you see another stop sign coming up soon, no need to rush there, just coast to it and no jackrabbit starts. I've always driven like that. That was in my first car, a used '66 Barracuda. White with green metallic leather interior. Wish I had that car now. I could sell it and buy Priuses for the whole family!

 

[LittleLamb]

The way my daddy taught me to drive

I think I meant "coast and pulse". But my dad was such a penny pincher, AND a notoriously slow driver that he never put his foot on the gas very hard. Once on our one vacation to Florida we were pulled over for going too slow on the freeway.

 

[wayneswhirld]

Welcome to the forum! The driving technique you may be referring to is Pulse & Glide. Basically, it's accelerating normally to the speed you want to maintain, letting off for an instant, then lightly accelerating as if you have an egg under the gas pedal. Then, when you gradually lose speed, reaccelerate again and repeat the process. On the Energy monitor, you're achieving P&G when there's no arrow activity--the most efficient state. This works up to 41 MPH and only works well to any degree on fairly level roads.

You seem to be referring more to an also very economical technique (or habit) of minimizing stop and go. By anticipating traffic patterns and lights well ahead, you can usually watch all the normal drivers accelerate faster than you and have to brake more quickly for other traffic or lights, while you catch up just as a situation "corrects" itself or a light has changed to green. I've been driving that way for many years! One caution though is not to go so slow that you're not sort of keeping with the flow of traffic, or annoy other drivers by accelerating way too slow...just be smart and sensible about it.

 

[LittleLamb]

"Welcome to the forum! The driving technique you may be referring to is Pulse & Glide. Basically, it's accelerating normally to the speed you want to maintain, letting off for an instant, then lightly accelerating as if you have an egg under the gas pedal. Then, when you gradually lose speed, reaccelerate again and repeat the process. On the Energy monitor, you're achieving P&G when there's no arrow activity--the most efficient state. This works up to 41 MPH and only works well to any degree on fairly level roads".

Thanks, wayneswhirld. This explanation of what to look for, or not look for, on the energy screen is the best yet I have read!

 

[DanMan32]

It is true thought that pulse and glide would work with an ordinary car, but maybe not to the same extent. For one thing, the ICE on an ordinary car is always burning fuel, even when no power is demanded of it to move the car. Also, the gearing would put a drag on the car even if you weren't pressing on the brake. Putting the transmission in neutral can negate that to some extent. A Prius can freewheel much like a regular car with a manual transmission with it's cluch disengaging the engine.

With the Prius, even if you have a little drag from regen, at least you get some of that energy back. You get none back on an ordinary car if you press on the brake, or even apply engine/transmission drag.

So yes, your dad was wise.

 

[ken1784]

For one thing, the ICE on an ordinary car is always burning fuel, even when no power is demanded of it to move the car.

This is not true any more.
A lot of current vehicle have the fuel cut mode.

[email protected]

 

[DanMan32]

Not THAT many (I would estimate maybe 5 models?), but I was being general.

 

[ken1784]

Not THAT many (I would estimate maybe 5 models?), but I was being general.

My guess is more than 95% of vehicle which are equiped with gasoline fuel injections have the fuel cut mode.

[email protected]

 

[LittleLamb]

I guess I just meant in general, it would save money if all cars would get better gas mileage if they slowed down, didn't accelerate fast to the next stop sign if its a short distance away and down a hill (like in our neighborhood), just common sense driving. I got better gas mileage driving a '93 Nissan Altima automatic than either of my teenagers did. Hmmm. Wonder why.

 

[LittleLamb]

Oh dear, that was a Freudian slip. I meant it would save FUEL, not money (although that is still a nice perk). I didn't buy my Prius to save money (my salesman made sure of that), I bought it to try and do my part to better the environment and leave a smaller footprint on the earth. Note to self: finish the whole cup of coffee before posting.

 

[DanMan32]

Not THAT many (I would estimate maybe 5 models?), but I was being general.

My guess is more than 95% of vehicle which are equiped with gasoline fuel injections have the fuel cut mode.

[email protected]

95% shut their engines off? Get real.

 

[TJandGENESIS]

Not THAT many (I would estimate maybe 5 models?), but I was being general.

My guess is more than 95% of vehicle which are equiped with gasoline fuel injections have the fuel cut mode.

[email protected]

Don't think so, but you know, I needed the laugh.

 

[ken1784]

95% shut their engines off? Get real.

No one wrote that "95% shut their engines off".

http://www.autoshop101.com/forms/h43.pdf
Goto page-7, and find the term "deceleration fuel cut".

[email protected]

 

[ken1784]

Not THAT many (I would estimate maybe 5 models?), but I was being general.

My guess is more than 95% of vehicle which are equiped with gasoline fuel injections have the fuel cut mode.

[email protected]

Don't think so, but you know, I needed the laugh.

Please note that this is Prius Technical Forum. A comment with a lack of technical knowledge makes one laugh.

For those who are interested in this topic, do google search using "deceleration fuel cut".
There are a lot of good articles about that.

[email protected]

 

[TJandGENESIS]

Please note that this is Prius Technical Forum. A comment with a lack of technical knowledge makes one laugh.


[email protected]

So, my 30 years of experience with cars of all types, having worked on them, built them, re-built them, and then, being an engineer on top of all that, does not qualify me for having 'technical knowledge'?

You, make me laugh.

 

[ken1784]

TJandGENESIS,
So, you have no knowledge how to google it.

[email protected]

 

[jamesfchumbley]

Please note that this is Prius Technical Forum. A comment with a lack of technical knowledge makes one laugh.

[email protected]

So, my 30 years of experience with cars of all types, having worked on them, built them, re-built them, and then, being an engineer on top of all that, does not qualify me for having 'technical knowledge'?

You, make me laugh.

TJandGENESIS, I think the problem is that your and my experience and degrees being from the United States are automatically discounted as nearly worthless by the "gentlemen of Japan." I have experienced it often during my countless trips to Japan. If I read his posting correctly, [email protected] is from Yokohama.

 

[efusco]

For one thing, the ICE on an ordinary car is always burning fuel, even when no power is demanded of it to move the car.

This is not true any more.
A lot of current vehicle have the fuel cut mode.

[email protected]

Ken,
This was your original post. Clearly your intent was to imply that many vehicles cut off fuel flow to reduce the amount of fuel being burned. Any logical progression would lend one to believe you meant to suggest that this was equivalent to ICE shut-off/fuel cut off during not only times of deceleration (to a set RPM limit), but during stops, coasting, etc.

Clearly that is not what happens. The article you referenced explains that the fuel cut off is very brief and ONLY during deceleration. Once the ICE RPM reaches a preset limit fuel flow begins again whether decelerating, stopped, whatever. This is not a fuel saving feature but rather something to make the ICE work better.

Your defensiveness in this thread is uncharacteristic.

 

[ken1784]

For one thing, the ICE on an ordinary car is always burning fuel, even when no power is demanded of it to move the car.

This is not true any more.
A lot of current vehicle have the fuel cut mode.

[email protected]

Ken,
This was your original post. Clearly your intent was to imply that many vehicles cut off fuel flow to reduce the amount of fuel being burned. Any logical progression would lend one to believe you meant to suggest that this was equivalent to ICE shut-off/fuel cut off during not only times of deceleration (to a set RPM limit), but during stops, coasting, etc.

Clearly that is not what happens. The article you referenced explains that the fuel cut off is very brief and ONLY during deceleration. Once the ICE RPM reaches a preset limit fuel flow begins again whether decelerating, stopped, whatever. This is not a fuel saving feature but rather something to make the ICE work better.

Your defensiveness in this thread is uncharacteristic.

Evan,
Thank you for your comments.
Maybe, my explanation was poor in English.

I would like to point out that Danman32 wrote "an ordinary car is always burning fuel".

Then, I would like to tell "deceleration fuel cut" mode does exist on current vehicles and that mode does not burn any fuel.

[email protected]

 

[efusco]

Ok,
So I think it's fair to say that deceleration fuel cut is fairly standard in Fuel Injector equipt modern vehicles and that to prevent back-firing during deceleration/rpm spin-down this mode is enabled. AND, there is no fuel being burned during this time--thus, DanMan's "always" comment would, indeed, be somewhat inaccurate even though generally is true. This would have a tiny affect to improve FE (but it must be nominal) and isn't the main reason for having it.

Finally, the fuel cut mode stops once a minimum RPM is reached (one example said 1100 RPM for the Honda Insight) and fuel is, once again, burned to prevent the ICE from stalling....thus fuel is always burned once the ICE spins down during coasting/deceleration and at stops unless the car also has ICE shut-off capability.