How to drive in the hills

[KV55]

Much of my driving is a landscape of rolling hills, typically going up and down 120 feet every mile or so, with very few stretches of flat in between. Pulse and glide is great for those 40mph drives along smooth flat roads but perhaps not the ideal way to get the best mpg when going up and down like a yo-yo.
I have been trying to go up hill with battery assist, whilst using the downhill stretches to recharge the battery. I find getting the into the battery assist state is not so easy and it means a healthy push on the accelerator, letting up towards the crest.
It makes sense to go up the steeper and shorter hills, and down the more gentle longer ones, so I try to pick a route that maximises this.
Anyone have any thoughts?

[efusco]

<div class='quotetop'>QUOTE(KV55 @ Apr 17 2007, 07:13 AM) [snapback]424534[/snapback]</div>

Much of my driving is a landscape of rolling hills, typically going up and down 120 feet every mile or so, with very few stretches of flat in between. Pulse and glide is great for those 40mph drives along smooth flat roads but perhaps not the ideal way to get the best mpg when going up and down like a yo-yo.
I have been trying to go up hill with battery assist, whilst using the downhill stretches to recharge the battery. I find getting the into the battery assist state is not so easy and it means a healthy push on the accelerator, letting up towards the crest.
It makes sense to go up the steeper and shorter hills, and down the more gentle longer ones, so I try to pick a route that maximises this.
Anyone have any thoughts? [/b]

You didn't mention traffic conditions or speeds or whether you have CAN-View or Scan Guage so that limits my advice giving ability. But living here in the Ozarks there's not much besides rolling hills.

What I do is almost the opposite of what you do (but again, without a good idea of how steep the hills are or your speeds you may be doing the best for the circumstances). The main commute roads I take are 35-45mph speed limit 2 lane roads usually with little or no other cars to be concerned about and I use CAN-View. I try to maintain ~1850rpm (1700-2300 range) on the uphill segments until I hit about 39mph. As I approach the crest of the hill I feather the pedal into a glide. I then sustain that glide as long as possible down the hill and up the next...if it's a small rise sometimes I can maintain glide only over that hill and pick up speed again down the back-side. If it's steep I'll usually start my 1850rpm acceleration when my speed hits ~35mph (maybe 30mph if it's truely a no-traffic situation).

If you're talking about steeper higher hills at highway speed you can forget all that, for the most part. Just accelerate up the hill to maintain whatever speed you're comfortable with...if you can keep the RPM at 2300 that's ideal, 3000 if you must, but do whatever you need to get over the hill. On the downhill side it's still better to glide and maintain momentum than it is to regen...remember that regen is wasteful compared to maintaining momentum....it's more efficient than slowing without regen.

Hope that helps...or at least makes some sense.

[Skwyre7]

I drove this type of route for the first year that I had the car. I just set the cruise control and let it go. Now I know better. When I drive over hill terrain, I usually keep a steady foot on the accelerator, keeping my RPMs around 1800-2200. Sometimes the battery assists, sometimes it doesn't. I usually end up slowing near the top of the hill, use the momentum to carry me over the top and back down. I'll try to get a good warp-stealth glide going all the way down and starting up the next hill. I'll hit the gas again, and so on. I'm nowhere near a constant speed. In fact it can fluctuate by 10-15 mph. Luckily, my wife likes to sleep in moving cars, so she doesn't get too upset. Hope this helps.

[hobbit]

Gently rolling countryside, to sort of sum up, almost *forces* you to
do exactly the right thing with the Prius. It's the dead-flats that
are sometimes the problem in certain speed ranges!
.
_H*

[bestmapman]

<div class='quotetop'>QUOTE(KV55 @ Apr 17 2007, 08:13 AM) [snapback]424534[/snapback]</div>

Much of my driving is a landscape of rolling hills, typically going up and down 120 feet every mile or so, with very few stretches of flat in between. Pulse and glide is great for those 40mph drives along smooth flat roads but perhaps not the ideal way to get the best mpg when going up and down like a yo-yo.
I have been trying to go up hill with battery assist, whilst using the downhill stretches to recharge the battery. I find getting the into the battery assist state is not so easy and it means a healthy push on the accelerator, letting up towards the crest.
It makes sense to go up the steeper and shorter hills, and down the more gentle longer ones, so I try to pick a route that maximises this.
Anyone have any thoughts?
[/b]

I am kind of new at this, but here is what I have been doing.

The hills in my area are steep enough to allow "coasting" downhill and not lose speed or I can even gain speed, Also I don't like to drive slow so I keep my speed up to 65 or higher all the time. I have tried using the warp stealth mode on the downhills. The problem with warp stealth is that the battery discharges and although this works good going down the hill, when I get down to the bottom of the hill, the battery has dischared quite a bit. On the next uphill the the battery usually charges and and this makes the engine work harder thus lower fuel economy. this tecnique usually yeilds me 45 mpg or so on the hilly area.

I have done some experimenting and I have found that in the "B" mode you can get into a mode that on the screen allows you to turn off all the power indicators like glide below 42 mpg.

How I achieve this:

On a downhill above 42 MPH retract the Go-Pedal all the way and reapply to enter Warp-Stealth. Once Warp-Stealth is achielved switch to B. Adjust the Go-Pedal (usually slightly more pressure) and all the energy flow indications will go out. Just as in low speed glide (below 42 MPH). The only time this will not work is if the battery is low. It seens to want to charge it one way or another then. I do not retract the Go-Pedal in the B mode as it goes into the high regen mode and slows the vehicle to much.

The end result is that at the end of the long downhill the SOC(State of Charge) is higher than if I went to warp stealth. It takes some practice but is easy to achieve once you learn how. This technique seems to improve my fuel economy 2-3 mpg in steep hills.

Some of the guys with the CAN-VIEW said that there is actually some fuel flow with this technique and there is none with warp stealth. I think that the small amount of fuel flow in the "B-glide" mode is more than made up for by not discharging the battery as much.

The other possibility is that there is no difference or that gliding in B doesn't make a difference and I am doing something different to get the better fuel ecomony. Like I said I am still new at this.

You may want to try it. If you do, let me know what happens.

[KV55]

<div class='quotetop'>QUOTE(efusco @ Apr 17 2007, 01:28 PM) [snapback]424541[/snapback]</div>

You didn't mention traffic conditions or speeds or whether you have CAN-View or Scan Guage so that limits my advice giving ability. But living here in the Ozarks there's not much besides rolling hills.

What I do is almost the opposite of what you do (but again, without a good idea of how steep the hills are or your speeds you may be doing the best for the circumstances). The main commute roads I take are 35-45mph speed limit 2 lane roads usually with little or no other cars to be concerned about and I use CAN-View. I try to maintain ~1850rpm (1700-2300 range) on the uphill segments until I hit about 39mph. As I approach the crest of the hill I feather the pedal into a glide. I then sustain that glide as long as possible down the hill and up the next...if it's a small rise sometimes I can maintain glide only over that hill and pick up speed again down the back-side. If it's steep I'll usually start my 1850rpm acceleration when my speed hits ~35mph (maybe 30mph if it's truely a no-traffic situation).

If you're talking about steeper higher hills at highway speed you can forget all that, for the most part. Just accelerate up the hill to maintain whatever speed you're comfortable with...if you can keep the RPM at 2300 that's ideal, 3000 if you must, but do whatever you need to get over the hill. On the downhill side it's still better to glide and maintain momentum than it is to regen...remember that regen is wasteful compared to maintaining momentum....it's more efficient than slowing without regen.

Hope that helps...or at least makes some sense.
[/b]

I have a scan gauge in the post so the rpm monitoring will be an option soon. The roads have other light traffic and I try to keep around 50mph or so but will go slow when there is no one around to see me :P

Some downhill sections can give me too much speed and so the battery gets a boost, so I try to put this to use on the uphill section. On Monday I noticed that by starting off at the top of a hill from stationary and in EV and then by backing off to the no arrows state before going through the 31mph EV limit, the no arrows state remained through to 50mph. I think this was too long a duration to be MFD lag. This might fit in with what bestmapman has, although I stayed in D rather than B mode. I will give the B mode a try to see how it compares with a very light touch warp-stealth.

[hill]

I basically go as slow as possible up the hill, than as many others do, glide over the top, then do a glide / nonrecharge down hill. That builds up way more speed for the next hill, where I do it all over again. Mileage seems to neither loose or gain using this technique.

[subarutoo]

Just drive the car. I think some of you guys are overthinking the process. Put it in drive, step on the gas pedal, and the car will figure out the rest. Don't forget to steer when the road turns. Sheesh.

[efusco]

<div class='quotetop'>QUOTE(subarutoo @ Apr 17 2007, 02:47 PM) [snapback]424820[/snapback]</div>

Just drive the car. I think some of you guys are overthinking the process. Put it in drive, step on the gas pedal, and the car will figure out the rest. Don't forget to steer when the road turns. Sheesh. [/b]

Thanks for the very kind advice...but no thanks.
"Just Drive It" is just fine, I don't condemn it and, in fact, encourage it to most people. But that's like telling someone with a 'vette to just drive the speed limit and obey the traffic laws IMO. What's the point of a performance vehicle anyway other than to enjoy and explore it's ability to perform.

The Prius IS a performance vehicle...it's just that it's performance is about high fuel economy and low emissions...some of us enjoy exploring the limits of those performance features. I don't know why that should bother you in any way, nobody's forcing you to do it, but why criticize those of us who do....Sheesh.

[chogan]

<div class='quotetop'>QUOTE(hobbit @ Apr 17 2007, 10:39 AM) [snapback]424601[/snapback]</div>

Gently rolling countryside, to sort of sum up, almost *forces* you to
do exactly the right thing with the Prius. It's the dead-flats that
are sometimes the problem in certain speed ranges!
.
_H*
[/b]

Yeah -- it IS pulse-and-glide, just minus the annoying change in speed you get using pulse-and-glide on the flat.