Prius and hills question

<div class='quotetop'>QUOTE(woffman @ Dec 13 2006, 05:21 PM) [snapback]361957[/snapback]</div>

It depends what you mean by "good on hills". My '05 Prius with 3 adults and one 8 year old didn't have any trouble on a drive this August up to the continental divide heading east out of Missoula. No more trouble maintaining speed than any of the other cars on the road, and faster than many. We had a fair amount of luggage as well, because we were meeting our son-in-law in Bozemann to deliver our daughter and grandson to him.

OTHO, uphill mileage sucks. Some is recovered on downhills, but far from all.

Dave M.

 

Welcome to PriusChat!

I live in the Blue Ridge Mountains and I do great averaging over 50 MPG.

Although you probably won't get the EPA estimates, who cares? You'll be leaps and bounds over your Dodge and saving the planet to boot. Don't hesitate to TELL your salesperson that you want to take the car on a nice long test drive. Mine offered to let me take the car for as long as I wanted! Anything less wouldn't be a true test drive.



As for hills...

Build up speed going down, and let the speed bleed off slowly going back up. Like many others have stated in previous posts, I think you should refrain from using the cruise control on hills. It's too agressive and actually makes for a less than smoothe ride especially as you begin to crest the hill.



Just do it!

 

I will be changing jobs very soon and will be driving around 750 miles a week. The terrain is rural and a lot of hills. How does the prius do on hills? I have heard info that they are not very good on long hills.

Welcome,

The big difference between my Olds and the Prius is that coasting down hills made my Prius decelerate (due to the regenerative braking) instead of accelerating due to gravity. This includes the grades through the Alleghenies in western PA. The Prius did accelerate down some of the state roads where the grade is steeper. Mileage was rather consistant in the very high 40's to very low 50's mpg. On rolling terrain I would keep steady pressure on the gas pedal downhill to use all of the momentum possible to get up the next hill.

I did not experience any undesireable handling characteristics.

 

<div class='quotetop'>QUOTE(woffman @ Dec 13 2006, 08:21 PM) [snapback]361957[/snapback]</div>

I have around 40000 miles on my 05 now and average overall 50mpg, whether driving on flats or hills. Economy is lost going uphill but regained coming back down. The cruise control works flawlessly and gets good milage plus releases one from the angst of the highway patrol. I drove across country and back at a consistant 60MPH and got 54MPG. The Prius gives one a odd persective at times, as I almost welcome highway slowdowns, thru towns at 35MPH and slowdowns for highway contruction. These opportunities increase my multi-display often to 65MPG. It's really nice not getting pissed off because the light turned red or having a heart attack because the traffic is crawling. I just smile now and pat my little ole MFD.

 

One thing to do is install an EV-mode switch and if you aren't in
anyone's way, drop under 34 mph near the crest of a climb and pop
into EV mode and try to use up the rest of the battery just as you
go over the top. Then you get more regen headroom on the down.
.
_H*

 

I've taken mine over some pretty high passes in the Sierras and never had a problem with keeping up (or passing) the other vehicles on the road. The last trip I took over Donner Pass (about 7000 feet) and back to the SF Bay Area the tank average was 50.6mpg. That was going 70-75mph when traffic allowed and probably a minimum of 60mph on about 25% of the trip. I think this would be a good car for your application.

Jeff

 

The general gist of what everyone is saying is this: The Prius will perform fine on hills and mountains - it can keep up with normal cars. You're FE (fuel efficiency, or mileage) probably won't be as good in hilly terrain as it is for people in flat terrain. However, the key to getting good mileage in any car is to learn how to drive it properly. A vast majority of people wreck their own mileage through their driving habits without even being aware. the suggestions offered in the thread here will help you get better mileage from a Prius, or quite possibly any other car you may be driving.

 

<div class='quotetop'>QUOTE(eagle33199 @ Dec 14 2006, 01:30 PM) [snapback]362274[/snapback]</div>

I have yet to take my Prius into any mountainous territory therefore this is just theoretical on my part, but isn't the regen braking system in HSD actually ideal for mountains or long hills, particularly on descent?

In a traditional car, the brakes in most cars will eventually "fade" from overheating over a long stretch; the Prius OTOH, will not use the friction brakes at all until near the end of the stop, or a panic situation. Therefore, concerns of brake fading would be practially non-existent (as well as the usual frequent brake jobs in this sort of driving!). For people living in mountains, it would be a safety issue; for those in slightly-less mountainous areas where the brakes don't heat as much, at leat they will save on brake pads.

Essentially, there is no need for "downshifting", as this is what the brake pedal essentially does, just in a much smarter way. Safer and save money on brakes. Works for me! B)

As I said, I have not had the chance to drive in this situation myself, but that is the conclusion I draw based on my understanding of the technology. If someone more knowledgeable than I knows otherwise, please advise.

Just my $0.02...

 

Actually, not on long hills. Once the battery is fully charged, it can't use the regen braking because it has nowhere for the electricity generated to go. However, there is the "B" mode for use when coming down from that mountain lodge in the Rockies.

So unfortunately, no, Toyota didn't solve this interesting little problem.

 

<div class='quotetop'>QUOTE(eagle33199 @ Dec 14 2006, 04:20 PM) [snapback]362436[/snapback]</div>

Maybe not solve it, but at least it is minimized since it will recharge the battery in full before using the friction brakes, so at least friction braking starts later.

 

My 2006 Prius is a champ up and down hills. The fuel economy tends to drop like a rock going up a hill, but the car never loses speed. And between the regenerative brakes and the engine brake, going down hill has never been safer. Depending on the grade and length of hills, sometimes the cruise control even handles them very well. (But sometimes it does a really bad job, as one would expect from cruise control.)

Also my dealer let me test drive a used Prius for 90 miles (home and back) to help me decide if I could adjust to all the weirdness of a Prius. That was nice. I'd have probably gone with a Matrix if I hadn't had such a long test drive to adapt to the Prius and start loving it.

 

<div class='quotetop'>QUOTE(woffman @ Dec 13 2006, 06:21 PM) [snapback]361957[/snapback]</div>

I drive up (and down) 10 miles of hill gaining and losing ~2000' and the car does just fine.
Yes, as physics would suggest, you get better mileage going down. Makes me wish I had a bigger battery!

 

My commute includes some hills, including the Conejo Grade on route 101 in Camarillo (a pretty steep hill). Over my 40 mile each way commute, my Ford Sporttrac got a steady 17 MPG and I had to take it out of overdrive and floor it to maintain my usual 75 - 80 up the grade.

The Prius is averaging 47.5 MPG over the same commute and attacks the grade without any problem. The ICE revs higher than you think it should, but with the CVT you don't get any downshifting. I can maintain the 75 - 80 MPH uphill without any problem (unless there's a stupid SUV in the left lane who can't figure out how to move over).

 

<div class='quotetop'>QUOTE(eagle33199 @ Dec 14 2006, 04:20 PM) [snapback]362436[/snapback]</div>

Now that's an interesting problem. I guess I had never thought about that... having too much extra energy. So you're saying this would actually cause the system to use the friction brakes when it wouldn't have otherwise?

How often does this "extra energy" situation arise? Any idea on how much energy (Whr) or power (W) we're talking about? I don't know that I've ever experienced it in my driving conditions. I think the amount of times that I've seen the battery at full charge (8 bars) is very rare. Then again, I don't do much mountain driving here in CT. Hills yes. Mountains no.

I have thought that it would be nice to have some sort of light or indicator that tells you when the friction brakes are activated - just to know, and maybe to use it to improve braking habits.

It seems like such a shame to have to throw away that extra energy on the brake pads. I'm sure this group could think of a whole bunch of interesting modifications that could take advantage of that extra energy. What do you think? Any good ideas out there? I've got a couple in mind, but I think they kind of fall into the "mad scientist" category, so I'll wait to see if anyone else bites on this before putting them out there.

 

Going uphill, (at least on an '05) you'll see the battery deplete itself to the 2 pink bars. I think you can go even further with an EV switch..
As others have suggested, if you know the route, use up all of the battery, so that you can soak up extra free energy going down the hill.

In general, once the battery is 'full', (look at the MFD) the friction brakes take over. Unless you're really paying attention, you won't notice it kick in.
It's really interesting to feel this transition, as soon as you get a full battery, your brakes will start to feel 'spongy.' Regen really does have a strong kick. It's about developing these senses that will really make the prius shine.

One should really be careful when it goes to normal braking, as standard precautions about not overheating your brakes will be important. With friction brakes, the rules are the same just like any other car..

Again, judicious use of the 'B' mode can help you optimize the use (and lower the temperature) of your friction brakes.

If you play your cards right, you can maintain a steady 60-70MPH for the entire descent. This is without any friction braking at all (until a stupid SUV cuts in front of you!)

danatt,
If it's even slightly warm outside, and I know I will have extra energy. I turn on the AC... If it's 100+degF outside, you can force the battery to drop 3+kW on the AC.. It is 'free' after all! Unfortunately, it only pulls 3kw when the compressor is running full blast..

 

<div class='quotetop'>QUOTE(woffman @ Dec 13 2006, 08:21 PM) [snapback]361957[/snapback]</div>

The full answer depends on what you mean by hills.

I agree with all other respondents -- no problem with getting up the hills. Drove my family over the Blue Ridge here in Virginia, with no problems keeping up speed.

On mileage, far as I can tell, sometimes the best terrain for gas mileage is gently rolling hills. Small-scale hills, where you can roll down one, pick up speed, and get partway up the next before you have to hit the gas. Elevation changes of a hundred feet or so. On that kind of terrain, you basically only run the engine on the top part of the upslopes, spend the rest of the trip with the engine off, and get great mileage.

Otherwise, if you're talking big hills (which I think the rest of the posters were addressing), then yes, your mileage won't be the best possible. My father lived in Western NY, and from what I remember of the terrain in Western NY, I'd bet you'd still get very good mileage. My impression, from posts on this issue, is that it's the guys in the Rockies, with the long steep downhills, who lose the advantage of regenerative braking when the battery fills up, who lose the most in terms of mileage. For others, that effect is less. It takes a pretty big hill to do that. So, it depends on the size and steepness of your hills. I'd guess there are (e.g) few stretches of the NY State Thuway that would do that (completely fill the battery on the downhills), but I haven't driven that in a Prius.

In Western NY, I'd worry more about the snow. In particular, you more-or-less cannot spin the wheels at all on a Prius. There are several threads on this board where Prius snow handling is discussed. Feelings are mixed, except for general agreement that the stock Prius tires don't cut it in snow. Being a Southerner I have nothing to add on that topic.

 

Wow!! that's alot of miles per week

Prius is no problem on the hills & mountains 'round here. In fact, until winter set in I was averaging about 49 mpg.

 

<div class='quotetop'>QUOTE(danatt @ Dec 24 2006, 11:28 PM) [snapback]366447[/snapback]</div>

actually this is one of my biggest pet peeves. my prius seems to want to maintain 6 or 7 bars at all times, and it will actually charge the battery while i am going UPhill. then i crest the hill with 7 bars, quickly get to 8 on regen, and then loose the rest. i don't have an ev button, but even if i did i couldn't easily go under 34 mph near the crest to empty the battery. this pisses me off.

i will start another inquiry into why it wants to stay at 6-7 bars.