How well does the Gen III Prius perform at altitude?

I live at mile high and average 53.6 mpg in my Gen II. I drove it to the top of Fall River Pass in Rocky Mtn Natl Park at 11796 ft above sea level last summer. Going down I did get to hear the battery fan for the first time (too much charging from the braking and coasting). Guess it was about time even though it had me worried. No problems with acceleration. From my home to Fall River Pass and back on back roads and I-25 (only going 70 mph on I-25) I got 55 mpg.

On the other hand driving into a stiff wind in 08 across E Colorado and Kansas and back, it was only 44 mpg (my worst ever 1000 miles).

Oh, it works at -16 and 100 degrees F just fine...

There are those who complain about the seats. I had no problems on the second trip but I might just be built for the seat. Other than your seat issue, the car will do fine.

 

Take the Prius and report back... I for one would be really interested in knowing how it does.

 

I agree with efusco. I live at 5000 feet elevation, and frequently drive mountain passes to the East, South and West. You will hear the ICE going up the grade, and the indicated mileage will fall, but you can maintain highway speed/traffic flow. Descending the grade, the HV battery will charge, and your average mpg will return to near the pre-grade average. I try to maintain the "sweet spot" while decending so as to not overcharge the battery. If the speed get too great, I use the "B" to slow down, and try to get back into the "sweet spot."

 

I have driven my fully loaded Gen II Prius through 12,000 foot passes without any trouble, and got 50 mpg combining the up and down. Your Gen III should do even better.

Tom

 

Mine has traveled 395 from Kramer Junction to just past Topaz. Then we took the Monitor Pass / Markleeville route to South Lake Tahoe. I don't know the elevation, but it was much lower than Trail Ridge Road (12183 feet) and Pikes Peak Road (closed at 12,950 that day) in Colorado on that same trip.

If this will be your Prius's first descent down a long steep grade, you may take a while to get used to the screaming B-mode compression braking. The Prius engine is small, so it doesn't have as much compression drag as others. I liken the sound to a giant vacuum cleaner under the hood.

My Prius has been down more than two dozen different long steep grades that completely filled the battery and seriously spun up the engine for substantial distances. On a few I've tried wasting as much accessory energy as possible -- headlights, AC, rear defroster -- but this is probably not necessary or very meaningful.

Pikes Peak was the only one I wouldn't care to repeat frequently. I kept getting stuck behind much slower cars downshifted into very low gear, right for their cars but very wrong for Prius. It was too slow to spin up the engine for adequate drag. That meant riding the brakes, which got very hot, necessitating several brake cooling stops. Prius really needs a B2 for this road.

I was actually fine at the mandatory brake checkpoint, 175F, where a required cooling off period is triggered at 300-something. But we stopped for the shop anyway, and saw only one vehicle flunk the temperature test. It was a 3/4-ton pickup with Florida plates. I think the plates were a greater indicator of the problem than the vehicle type.

These hills will be a learning experience, and a few Prius drivers will strongly dislike them. But other than PP, I won't hesitate to repeat any of them.

 

I live at 9600 feet and regularly drive over steep high passes. Compared to my son's gen II the main thing I notice is the added power of the Gen III engine allows me to actually charge the battery going up many passes. With the Gen II as soon as you hit the steep parts it starts draining the battery and depending on the length of the pass you can run out of battery before you get to the top, leaving you in a rather underpowered situation. With our gen III I have yet to find any pass that is too long and steep to not maintain battery. For most of the windy passes, even fully loaded with 4 people and luggage at over 11,000 ft, I'm limited by tires and suspension not engine (or those pesky speed limit signs). It's actually kind of fun flying past folks on one of my frequent drives (Monarch Pass, CO) and seeing them in my mirror pointing. I can imagine them saying something like "That was a Prius. I didn't know they could do that. Must have a stuck accelerator..."

I haven't taken our Gen III over the west side of Vail pass yet but that might be one place I might be able to deplete the battery since it is long steep and relatively straight with a reasonably high speed limit.

These high-altitude, highway-speed drives are not ideal for the hybrid design. For this kind of driving a TDI would probably be better technology. However, we still averaged low 50's last summer and mid 40's this winter, even with poor road conditions, headwind, and snow tires (measured at the pump) so I have absolutely no complaints.

 

The third-gen added a BARO sensor in the inverter, to give the
system some idea what altitude the car is at [or at least what
the ambient pressure is], so that it can make certain compensations.
There are some weird pressure effects on the NiMH batteries that
happen in the second-gen cars, which evidently causes them to
use much more of the charge on the way up. It doesn't hurt the
car any, and personally I'm happy to drop in behind a semi that's
also crawling up the hill at 35 mph and enjoy the scenery, but
other folks succumb to the fabricated american need to blast
up all the hills full-bore.
.
_H*

 

I've had my Gen II over that pass, and it did fine. I did get stuck behind a loaded pickup truck crawling along pulling a trailer. When the overtaking traffic cleared, I pulled out and went around him. By that point my HV battery was all the way down, and it took a looooooooong time to get back up to speed.

Tom

 

Report back - please.

 

Just a quick note for other readers: you cannot overcharge the battery. The car will prevent this by automatically using the ICE to pump air (Jacob brake), to slow the car down. When the battery reach its maximum tolerable charge, the system will stop using regenerative braking.

 

I drive 395, 80, and 50 on a daily basis. The Gen III handles them with no issues what so ever. The downhills sort of balance out the uphills and I average 55+ in good weather, so no worries there either.

If you see a blue Gen III on your drive - give a wave!

 

I should add - we are expecting a blizzard over the next 24 hours, and predictions of snow and very cold weather through Thursday. Things are supposed to start to melt and warm up starting on Friday.

Which ever car you bring - if you are headed out this week be sure to bring some cables/chains with you.

 

We live in Northern New Mexico, have two Prius Gen IIIs and are accustomed to the benefit of less dense atmosphere at higher elevations... I frequently log trip averages of 57 - 62 mpg for mountain driving, mean temperatures having the greatest effect... I did a trip last September of 160 miles at elevations between 6000' and 9500' and netted 62 mpg. I'm certain that the less dense air contributed to the impressive average. Pilots know that the point of diminishing returns is roughly 8000' MSL for fuel burn vs airspeed... the sweet spot for Prius' is similar in my experience.

 

Over the last weekend, we took our 3 day old 2010 III to Lake Arrowhead, about 30 miles from San Bernadino. The trip went quite well without a hitch. We climbed up to approx 5500 ft and the car handled it pretty well. On the trip back, I had to read up the manual on engine braking (= Gear 1 or 2 in our other car) and also called up the dealership. The manual was not very detailed and the dealer had no idea how to climb down a steep grade. Luckily our Verizon 3G connection hooked us up to wikipedia that mentioned the use of down shifting to "B". That technique worked great and avoided us overheating the brakes. The trip netted 48 mpg.
Looking back, I guess we should have waited a bit before breaking-in the car on a steep grade

Also, I don't know if/how the prius handles snow / sleet.