I just got my Prius; it still has less then 300 miles on it, so I'm still getting the hang of it. I'm getting about 49 mpg according to the computer so I'm quite happy.

I've yet to try "pulse and glide". My concern is that it will be confusing to drivers around me and might actually be dangerous.

I commute on fairly crowded New Jersey rush-hour highways. Perhaps P&G is more appropriate on the wide open stretches in the West?

What do you think?

 

At all times you should always take into account the other traffic around you with anything you attempt to do.

I drive like a hypermiler in my TCH, and I am constantly on the watch in my rearview mirror for traffic patterns that might force me out of what I want to do, which is usually attempting to achieve EV mode, or else keep the cruise on 34 MPH.

My commute is City streets only, most of the way it's two lanes in one direction, sometimes three lanes. I just stay out of people's way by knowing what's coming up ahead and behind me.

The only time I intentionally "bother" other drivers is in this one situation:

If I know ( based on watching it or just knowing the cycle of a red light that driving the speed limit when approaching within 8-15 blocks of a red light ) that a light is going to be red when I get there, and there are people behind me, I drive as slow as I want to when I KNOW the light is going to be red when I get to it.

If someone is stuck behind me, then that's just too bad. I'm not going to SPEED to hit a green light, and I'm not going to ZOOM UP to a red light. I'm just not.

P.S. As far as I know, there has NEVER been an accident attributed to Pulse and Glide or any other Hypermiling technique.

 

It has to do with the route and traffic and yes, you don't want to do "pulse and glide" in the middle of bumper-to-bumper rush hour. Let me suggest you first 'think strategicly' and then look at the tactics.

Start with a Google or Mapquest map of your daily commute route. Then look at the alternatives and try them. Your goals should be:

1) speeds of 0-38 for stop and go
2) speeds of 51-65 for sustained highway
3) 1-2 mile warm-up ~25 mph for first segment
4) ~2 mile EV mode, 30-35 mph for the last segment

Try to avoid the 39-51 speed range.

Now looking at your route, first map out 'warm-up', especially in the first trip. It is not so much a problem on the evening return but it really helps in the morning. Once the vehicle systems are fully warmed up, you drive it normally.

Then find a nice 30-35 mph, ~2 mile length street at each end that you can maximize your EV (electric vehicle) operation. The NiMH batteries lose some charge when just sitting there. Rather than lose that energy, use it to 'silently' go the last mile or so. This is usually an excellent choice for the warm-up.

Now look to see if there are practical 'shorter distance' routes that you used to avoid because they were slow. Your Prius pays no MPG performance when you are going slow and if you can anticipate your braking, even stopping is pain free. A good radio or music is a great asset making it easier to calmly finish the trip.

If you work out the trip strategy, you'll get excellent mileage and get there happy. To see what I mean:



As you get familar with the car, you'll find places where with a well designed commuting route, you can maximize MPG performance. You might also want to consider the EV button modifcation from Coastal Electronics. This too can, if used sensibly, give better MPG performance.

GOOD LUCK!

Bob Wilson

 

Bob,

Thanks for the graphically concise advice! After 3 1/2 years of the same commute, I think I've found the sweet route for my own enjoyment. I'm already getting 49 mpg on it (after getting 22 mpg in my Bonneville) so I'm very happy.

But I'm wondering how to maximize my efficiency. Perhaps you might suggest?

I have an 8 mile stretch at 35-45 that goes over rolling hills with one long downhill where I get infinite gas milage. Then 45 miles of highway with a 4 mile tie up along the way. Then a mile of streets.

I'm trying to glide as much as possible on the rolling hills, but every slight incline triggers the ICE. This is where the EV button might come in handy. There's just one hill that really needs gas. Is there a way to go up a mild incline w/o gas?

On the highway I really like the zen of steady speed, but I've heard that p&g can become so ingrained I won't be conscious of it.

What is the right method? Pulse up to 70 mph and then glide until my speed is 50 mph, then do it again? Is it glide with no accelerator or with as much accelerator as possible w/o triggering the ICE? Should the pulse be gradual or firm?

Thanks for helping a newbie.

David

 

David,

See this page for a great piece on P&G in a Prius II:

http://www.cleanmpg.com/forums/showthread.php?t=1224

 

Others will no doubt chime in. I'm not the expert in all Prius operational modes but I'll share what I've found works.
Try to avoid transitioning through 42 mph because that is a threshold that either lets you run with the ICE off or to protect MG1, the ICE must run. Although the NHW20, your model, has a higher maximum RPM for MG1, I understand the same control law applies.

It is OK to go faster than 42 mph and stay there or under 42 mph (with guard band, 38 mph) and stay there. It is the transit through that puts the vehicle in a mode where it has to expend energy starting or stopping the ICE that needs to be avoided. That is why I recommend 0-38 and 51-65 mph as optimum speeds and try to make sure the +42 mph times are long enough, +1 mile, to make up for the accelleration energy loss.

As for hills, the best rule for fuel efficiency is up as slow as practical and then down whatever is comfortable. If "D" controls you speed, good, feet on floor. Others have and I'm tried using "B" to reduce speed, foot on floor, to avoid using the brakes. You can flip between "D" and "B" at any speed, it is an electronic, not a mechanical shift.

The EV button is a good approach but it too is limited by the load. The faster the load, the more likly it will kick in the ICE. There is one impractical exception, reverse.

I've heard that too and I've used 'N' in the past. However, classical P&N is below the 42 mph limit.

There is a new technique called "hyper glide" that promises to extend high efficiency driving into speeds above 42 mph. However, the descriptions have convenced me that instrumentation is needed. But all of the manual processes suffer from one defect, they are manual.

To make them work, the early developers used instrumentation and then later described how to do it w/o instrumentation. I admire the effort but IMHO, without accurate instrumentation, you are 'driving blind.' BUT DON'T LET ME DISCOURAGE YOUR EXPERIMENTATION! I just prefer reproducable results.

In the Prius, classical P&G is below 42 mph. The "hyper glide" is a 'sweet spot' where the battery drain is low enough to keep the engine in a turning but 'no gas' state. The absence of quantitative numbers on the current Prius display makes that improbable to achieve (unless you have an exceptionally fine ability to translate English into engineering units by your foot.)

One thing for sure, treat an air-speed of 65 mph has your top limit. The MPH vs. MPH charts show 'bad things'(tm) happen starting at 65 mph:


Bob Wilson

 

I believe you'll soon achive 60+ mpg mark.
As Bob mentioned, the keeping below 42 mph is the magic key at slow road.
You shold install EV button for such conditions.
On above 42 mph highway, there is no magic. Just slower is better.
Or, you can do your own experiment. It is good to take notes everyday including outside temp, mileage number and trip. You can calc daily fuel usage from these numbers.

Good Luck!

Ken@Japan

 

Today I got consistently over 50 mpg for the highway segment of my commute.

I tried accelerating up to 65, sometimes 70, in the fast lane, then moving into a slower lane and gliding back down to 50. I'm also realizing that I'm paying more attention to the terrain. I'm trying to anticipate a hill coming up and gliding until forced to accelerate.

Does a short burst of strong acceleration use less gas than a slower sustained acceleration? Or since the change in momentum is the same is the gas usage the same?

Does anyone know how much the EV switch costs and where to get it?

Thanks,

David

 

Coastal Electronics in Florida $45 + S&H (and you get a small box of jelly beans). I think there is also a headlight stalk mod but the idea of flashing the highs when you put it in EV is not desireble (to me). You can also buy the OEM button but when I looked into it, it would cost $50 shipped from Japan AND I would have to make my own wiring harness. For < $50, I went with the Coastal mod. Works well, easy to install (especially in the second Prius ) In no case do you get an indication on the dash that it is in EV mode like the European and Japanese Prii that come with the button. Still not sure why we in NA can't get it even as an option.

However, Ken's comment about getting the EV switch: is incorrect, the EV mode - Coastal's CC stalk mod, an OEM switch or a Radio Shack switch - will kick out at about 34 MPH. They are all telling the computer to do EV, it does not know how the signal was generated. The computers will not engage CC while in EV mode so you do have to watch that you don't go over 34 (32 is safer for a little buffer) to keep it in EV.

 

The normal speed on the road where I would use EV is about 40 mph. You're saying that it wouldn't be safe to use EV there? If that's the case, then I'll skip it.

Ken said 40 was OK. What's the reason for the lower limit you state?

Thanks,

David