Comments on Steep Mountain Driving

I averaged 55 mpg going over the Rockies.

It's a 1.5 liter engine. What do you expect? If you need more power, floor the pedal. That's why it is there.

Going uphill takes more gas. It's a simple matter of physics. The good news is that you get a lot of it back going down the other side.

So would you have the car automatically apply the brakes? The Prius has low drag, and coasts very well, so it will accelerate downhill.

B mode is not dependent on the length of the hill. If you need it, use it. As for most short hills, use the brakes. That's why the Prius has regenerative braking.

It has a bigger engine, so yes, it does better on hills, not that the Gen II is too bad.

True, but many do. Many don't have snowy winters, but many do. PriusChat has members from all over the world.

Tom

 

I've been all up and down the Sierra Nevada range (east and west)as well as trips to Vancouver BC. and while the super long steep grades can be annoying I don't find it such a big deal. Esepcially for the MPG return. I'll deal with a lack of power for that tradoff. The only time I've been concerned was on the grade from Sacramento to Reno in the dead of winter where the engine just seemed to rev forever and the battery charge indicator stayed in the red for a long time and power was sluggish. I still never considered it unsafe and it was no wore than trying to drive my T/A with a 4400 stall converter up the same grade. lol

 

Yes, not much choice. It beats getting run over. Long steep hills are why I asked about the possibility of a turbo. The 22% extra power of the 2010 should make a big difference.

The Prius glides nicely, doesn't it? Use the brakes as you need to, crank up the air because it's 'free' anyway, and save as much momentum for the next uphill as you dare.

Ha. That 17's just a bump.


edit: Jinx! How did we do that - three answers at the same time?!

 

That it does!

Hyo, Tom beat us both by a decent margin. Lets grab a bar of soap and a tube sock.....

 

A hill-climb test provides a lot of insights to how much excess power our 1.5L Prius has:

For a 6% grade, the worst MPG corresponds to the speed where the engine is providing all of the climb energy. At slower speeds, the engine tunes into an efficient band and at higher speeds, the vehicle draws on the limited traction battery energy.

What this chart suggests is climbing a 6% grade is best done at ~55 mph. Much faster and the engine has to tune from Atkinson into a less efficient, power generation mode. In fact, the engine has to run rich to avoid damaging the catalytic converter, something the exhaust recirculation system handles in the 2010. Fortunately, 55 mph is the same speed many semi-trailer trucks use when climbing steep grades.

As for "B" versus "D" and brakes, I've never found shifting between the two to be a problem. Best of all, I know that is reduces 'heat pumping' of the traction battery:

Of course, it is your car and drive it like you want.

GOOD LUCK!
Bob Wilson

 

The downhills are the fun part. I just let it fly. :madgrin:

 

As I grew up in Santa Cruz and work in San Jose, I frequently drive 17 when visiting my mom who still lives there. I average much better driving south than north because the frontside going south is much steeper and shorter than the gradual drop off and longer length of the back side. The effect going south is that the engine works at a harder load for few RPMs to get to the top and because of the grudual drop off on the backside, I can glide all the way down most of the way.

However, going north, the engine is on for a much longer time at a much lower load to get to the same altitude, and then because the backside is so steep, I max out the battery at 8 bars and waste a bunch of engergy on the steep back side.

I average about 60 MPG going south vs about 40 MPG going north.

As long as the battery is charged, the Prius passing is quite impressive for what it is. From 70 to 90 MPH it pulls as many gs on on my G-Tech as my SC400 which has 250 peak hp. That's because the software allows more juice to the MG2 at higher speeds than at lower. If all 295 ft lbs of torque were release at launch, the wheels would just spin but the traction management prevents most of the MG2's potential from being realized at the lowest speeds and only gradually allows more as speed increases.

For this reason, 0 to 60 on the Prius is about 10 seconds while the SC400 is about 6.5 seconds.

Car and driver did a shootout between the Civic Hybrid, Prius, Jetta and Echo:

Honda Civic Hybrid vs. Toyota Echo, VW Jetta GLS TDI, Toyota Prius - Sedans/Comparison Test/Reviews/Car and Driver - Car And Driver

Download the power train chart.

Notice all of them are roughly equal in 0 to 60. Look at the Echo vs the Prius. The echo slightly edges out the prius in 0 to 60, but then look at 50 to 70 pass. The prius crushes the echo by more than a second. In fact, it completely crushed all of the other cars in the test in passing acceleration by even more than the Echo.

Although not shown in this chart, the effect is much more dramatic from 70 to 90 MPH as the torque multiplier gets less torque from the engine to the wheels for all of the cars the faster they're going, but the Prius pushes more juice into the MG2 the faster you go, as long as you have decent charge. The prius passes as fast from 79 to 90 as it does from 50 to 70, yet any regular gas powered car will always take longer from 70 to 90 than 50 to 70.

 

No, don't hurt him. He's a nice guy. :grouphug:

 

And how about 8.5%, with a fully loaded car? I don't sense much excess power then.

 

I was in San Jose about 2 mos. ago and made that Hwy.17 drive several times.....(nice little road) ...as I was driving a Altima hybrid...I wondered how beautifully my (left at home) Pri would have done.
The Altima hybrid, of course, has more power, but in the trade off, less mpg, although it drives and handles nicely.
----Of course, I would have used the "B" going down the mountain on my Pri.....that's what it's for........
And I totally agree-----that terrain was not that steep, considering, and I know my Pri would have handled it very adequately......

Oh, and I learned to drive many years ago and practiced on "The tail of the Dragon" route 129----113 curves in 11 miles........and when I'm back home.....the Pri does this drive well.

-------you might check it out----- www.thetailofthedragon.com --I don't have to recomend the drive, it speaks for itself.
-----just chatting-------"talk amongst yourselves"

eace:

 

I live at the top of an 11% hill of about a kilometre. I accelerate up this hill from the 70km/h speed limit at the bottom to sometimes about 90km/h which is 10km/h over the speed limit. I need to be careful of my speed because I once coped a fine at the top of this hill for 11km/h over the speed limit. I never have trouble getting up this grade and I don't seem to lose any bars on the battery. There is an alternative road with about an 8% grade and 100km/h speed limit. I need to be equally as careful on this hill.

I use the brakes to control my speed on descents unless the hill is so long it will charge the battery to capacity before I hit the bottom of the hill, then I use B.

I never worry about the engine noise on hills, the Prius engine is restricted to 5000rpm which is much lower than the conventional ICE in a Yaris which can rev to over 6,000rpm so even at full song the Prius engine is getting an easy ride. Because the Prius is normally very quiet there isn't much sound deadening material to keep the engine noises out when climbing steep hills. Just drive it.

 

A very interesting fact that I wasn't aware of.
The torque MG2 is able to deliver is always amazing.

I want to try a 100 to 160 km/h contest with some proud VW Passat TDIs, the car always in front when we speak of the Prius (the price put it as a direct competitor here in our market).

 

I've driven a 08 Prius between Santa Cruz and San Jose many times and I usually average about 48 mpg if I drive responsibly. This is on a rental with the A/C running, so the mileage could potentially be better if the tire pressures were correct.

From my experience, the Prius does struggle a bit on the steeper portions, but you can minimize fuel consumption by keeping your speed at 50 mph during most of the Highway 17 drive. By keeping your speed at about 50, the engine won't have to work very hard and you will not need to press the accelerator down more than 1/2 way in order to maintain your speed.

 

And given that the speed limit is 50 and that pass is *very* dangerous, it's a good idea anyways

 

It's actually 55, but I usually drive on the right lane with the Prius since the car does not handle well enough for the left lane.

 

Maybe you need more practice driving it? I sling mine around twisty mountain roads all the time and don't have any problems staying ahead of just about everyone not driving a Corvette or Miata. lol

Could be you were running on nearly flat tires (manufacture spec).

 

It was a rental and the tires felt a bit underinflated, so I didn't want to test my luck.