High Altitude Driving?

[Bigmikelakers]

I've curious about this. Driving somewhere say I-70 in Colorado at 10k Ft, does your car or even yourself feel different at that altitude? Does your car feel like it has less power? Do you yourself breath heavier? I ask this because next week, I plan to drive from LA to Sedona via I-40 and the stretch in the Flagstaff area is over 7k.

[oscar]

I've curious about this. Driving somewhere say I-70 in Colorado at 10k Ft, does your car or even yourself feel different at that altitude? Does your car feel like it has less power? Do you yourself breath heavier? I ask this because next week, I plan to drive from LA to Sedona via I-40 and the stretch in the Flagstaff area is over 7k.

Lots of individual variation.  Even though I live at sea level and am not in good physical condition, 7000 ft. altitude is no problem at all unless I'm hiking uphill, or doing other serious physical activity.  Even driving over 13000-14000 ft. (Mt. Evans and Pikes Peak highways in CO, Mauna Kea in HI) hasn't been a problem for me, except a bout of altitude sickness on the second of several trips to the Mt. Evans summit.  OTOH, I know people who complain about altitudes only one-tenth as high.  So YMMV.  

Cars react differently as well, in ways that might surprise you.  For example, my Prius seems to get better mileage cruising at high altitude, with lower aerodynamic drag offsetting any reduction in engine power.  (But the Prius definitely sucks on long high-altitude grades, the hybrid electric battery runs out of juice halfway up to the summit, and you're left with the little putt-putt gas motor to limp the rest of the way uphill.)  OTOH, turbo/supercharged engines might suffer no power loss at all.  My pickup truck, with lots of power to spare (and correspondingly sucky gas mileage), also doesn't noticeably suffer from high altitudes.

[huskeroadgeek]

I've curious about this. Driving somewhere say I-70 in Colorado at 10k Ft, does your car or even yourself feel different at that altitude? Does your car feel like it has less power? Do you yourself breath heavier? I ask this because next week, I plan to drive from LA to Sedona via I-40 and the stretch in the Flagstaff area is over 7k.

I would say as long as you are just driving in your car, you shouldn't notice much at 7,000 ft. Personally, I don't feel much different just driving in a car until about 10,000 ft. I may be somewhat more high-altitude tolerant than some people though-I've never experienced altitude-sickness(other than drowsiness) despite frequent trips to Colorado as a child and adult. The only difficulty I've really experienced is doing some hiking at the Trail Ridge Summit Visitors Center in Rocky Mountain National Park and hiking to the summit of Mt. Evans from the parking area(a fairly short hike, but even that left me winded and that was when I was in better shape than I am now).

[corco]

I definitely noticed my car had less power when I lived in Wyoming- especially driving to/from Rawlins and Cheyenne from Laramie on the gradual uphills. My car often had trouble getting up to 60-70, when it can easily go 90+ down here in Tucson. That said, I'm not sure how much of that was altitude as opposed to wind.

As far as myself, I think altitude makes a huge difference- when I moved from Wyoming to Tucson I suddenly found myself able to ride my bike 2-3 times as far at a much greater speed. I was perpetually out of breath in Wyoming after even the slightest amount of physical activity, but not at all here. If you're just sitting in the car driving you shouldn't notice a difference. If you have been on an airplane, those cabins are usually pressurized to 8000 feet or so, so it should feel like being on a plane.

Another thing to watch is your golf game. A well-hit 4-iron at 7000 feet goes as far as a well-hit driver at sea level, at least for me.

[realjd]

I can't speak for how cars run that high, but I doubt you'd feel much effect from the altitude just driving through. Do you feel different when you're on an airplane? They only pressurize those to about 8000' ASL.

When I visit Denver (~5000') I do feel the altitude a bit, but only when I'm doing something that involves exercise. I'm not in terrible shape here at 30', but I do notice I have a bit more trouble breathing even with light exercise like climbing a couple of flights of stairs. Just driving around? No problem. I find the extrordinarily dry air much harder to deal with, especially coming from Florida.

[Kacie Jane]

For both myself and the car, I don't have any problem with high altitudes.  It's the climb that's the problem.  (For myself, my ears will pop at the slightest pressure change.  For the car, obvious reasons -- I've never owned anything particularly powerful.)

[Bigmikelakers]

A few weeks ago, I took the Palm Springs tramway and, at the top where it ended, the altitude was over 8500ft. Walking up the slightest slope felt like I ran up a flight of stairs. Very odd feeling. I know Flagstaff is almost as high and so is the Grand Canyon so I hope I'm ok there next week.

[agentsteel53]

I consider myself fortunate to have never experienced any altitude acclimation problems.  I can drive up and down mountains all day, and I spent nine months living at 6800 feet (after living at approximately sea level the rest of my life) without any problem whatsoever.

then again I've never tried hiking a 13000 footer or anything...

[Sykotyk]

Word of advice, don't carry a bag of unopened potato chips, etc with you from low elevations up to Vail, the bag will pop. Shampoo bottles have done that to me, as well.

As for feeling sick, etc, not sure. Probably wouldn't notice it unless you sprinted and tried timing yourself.

[realjd]

One thing I forgot to mention: watch the octane ratings of your gas. Regular Unleaded up in the mountains is 85 octane vs. 87 at lower elevations. Your car will run fine on 85 at high elevations provided you stay up there. If you fill up with 85 and then drive down to a low elevation though, you could have engine knocking and other problems. So before you drive down, fill up with their midgrade (87) or, if you you still have a half tank of 85, their premium (91).

[oscar]

One thing I forgot to mention: watch the octane ratings of your gas. Regular Unleaded up in the mountains is 85 octane vs. 87 at lower elevations. Your car will run fine on 85 at high elevations provided you stay up there. If you fill up with 85 and then drive down to a low elevation though, you could have engine knocking and other problems. So before you drive down, fill up with their midgrade (87) or, if you you still have a half tank of 85, their premium (91).

Good point, though not often an issue, since gas sold in mountain areas within a tank-ful of lowlands will be at lowlands octanes.  Like in the Sierra Nevadas of California, which are high enough for 85 octane to work, but are within a few hundred miles from places at sea level, so the unleaded regular sold in those mountains is 87 octane,

[Duke87]

Some perspective: at 12,000 feet, about 45% of the Earth's atmosphere (in terms of mass) is below you. So, you're functioning in 0.55 atm. I have a 24 oz Pepsi bottle lying around somewhere that I last opened at 12,000 feet. It's pretty well crushed, just from the difference in pressure.
Or, how's this for a little fun - tub of margarine at the supermarket in Estes Park:


You don't notice it so much if you're sitting still, but you absolutely do if you try to exert yourself at all (who knew walking up a hill could be so much of a struggle?).

I didn't get a chance to actually get behind the wheel in Colorado (too young to drive the rental - hell, I had just gotten my license a week ago at that time!), but my father had no comments about it feeling strange.
Although, it was annoying coming down from the mountains - the minivan we rented had two low-gear settings: 1st gear (too slow) or 1st-3rd gears (too fast).

[J N Winkler]

Cars react differently as well, in ways that might surprise you.  For example, my Prius seems to get better mileage cruising at high altitude, with lower aerodynamic drag offsetting any reduction in engine power.

This is only to be expected, since aerodynamic drag is proportional to density of air and either the square or first power of speed (depending on speed).  But I'd say the improvement in fuel economy is more dramatic for cars with conventional propulsion because the engine is running 100% of the time (no partial dependence on electric power) and the low atmospheric pressure reduces the amount of fuel needed to maintain a stoichiometric mixture.  For both conventional cars and hybrids, however, the greater frequency of long uphill grades at higher altitudes offsets some of the efficiency gains.

[Bigmikelakers]

One thing I forgot to mention: watch the octane ratings of your gas. Regular Unleaded up in the mountains is 85 octane vs. 87 at lower elevations. Your car will run fine on 85 at high elevations provided you stay up there. If you fill up with 85 and then drive down to a low elevation though, you could have engine knocking and other problems. So before you drive down, fill up with their midgrade (87) or, if you you still have a half tank of 85, their premium (91).

Oh wow. Thanks for the advice. I never knew that.

[mightyace]

Around what altitude to the high altitude effects become noticeable?

In the Smoky Mountains, there are many places above 4000' and a few above 5000' (I know that's nothing compared to out west.).

My thought has been that it is not much of an issue since you don't stay that high for very long.

[froggie]

Probably at the 8-10K range.  At 5K elevation (which my car's never had a problem with), you're still at about 85% of the atmospheric pressure at sea level.  That percentage drops to about 70% at a 10K elevation.

[J N Winkler]

Around what altitude to the high altitude effects become noticeable?

It is a continuum without a sharply defined threshold value.  In my experience the physiological effects will become noticeable around 7,000' though they can creep up on you unexpectedly (e.g., syncope after a hot shower).  This is also the altitude at which fuel consumption effects become obvious.  Altitudes of 9,000' or better will seriously complicate high-speed driving.  I have had problems holding gear going over both the Rabbit Ears and North La Veta passes (both 9,426'), although the latter is much easier because the gradients are much lower.  The Berthoud Pass (11,000' plus) has a nasty reputation because of its high altitude and steep grades (6.3%), but when I took it in a car in the northbound direction, I found it easy to manage because the switchbacks limit running speed anyway.  You just crush the throttle pedal to the floor and keep climbing.

I have been through the Smokies and as far as I am concerned, they are more or less like being at sea level.  In Kansas the altitudes range from 4,039' (Mount Sunflower) to 679' (Verdigris River), and it is not really possible to feel any altitude effects anywhere in the state.

[myosh_tino]

The highest point I've ever driven across was Donner Pass on I-80 in the Sierra Nevada mountains (elev 7,240').  During my numerous trips to Reno, I haven't noticed any difference in the behavior of my car while driving over the pass.  What I do experience is the popping of the ears as I climb the Sierra Nevadas due to the change in air pressure.

A drive I want to make some day is the I-70 drive through the Eisenhower tunnel at an elevation of over 11,000'.

[SSOWorld]

I actually walked up a hill (not very steep) at summit on Trail Ridge Road (Rocky Mountain NP) in 2004 and could only take 10-15 steps before I was panting.  I haven't paid too much attention in terms of cars, but i've noticed a slight lag in speed (before the downshift kicks in) when climbing the Apps in Pennsylvania, New York or Maryland/West Virginia.  I haven't tested my car on the Rockies yet.

[mightyace]

Donner Pass is also the highest point that I've driven in a car.  It was a rental Malibu that I'd just picked up 2 hours earlier so I didn't know what was "normal" to the car.

The highest that I've driven a car I own was the National Park Service overlook on US 441 at the NC/TN border which is 5000' or so above sea level.

[berberry]

The people who have the most trouble are older folks who already have breathing problems to some degree.  Even minor problems can be exacerbated at high altitudes, so someone who, for instance, occasionally requires oxygen can expect to need it more than usual.

Conversely, going significantly below sea level can help some people who ordinarily require oxygen to temporarily live without it.  Air pressure increases, of course, as you go down, and since oxygen is one of the heavier gases in our air, more oxygen is present at below-sea-level surfaces.  For this reason, the Dead Sea - the lowest place on earth - is a popular tourist destination for those with moderate breathing difficulties.

AbE:  Come to think of it, cars with "breathing problems" should do better on the Dead Sea Highway, since for most of its length it's quite a bit below sea level.

[Truvelo]

Last summer I drove from Denver to Albuquerque along US-285, US-64 and US-550 and didn't notice the car was especially slow. It was a Camaro with 300hp. Perhaps if I had a city car with 60hp then I would have to change down to a low gear doing 20mph up hills with the engine screaming at 6000rpm