4WD or AWD to visit Mauna Kea?

[Kelena]

I guess I really don't know the difference between a four wheel drive (4WD) vehicle and one with all wheel drive (ADW). All of the signs at the visitor's center say that 4WD is required and I assume they mean it to the exclusion of AWD vehicles (although I have seen some cars at the summit that I am pretty sure do not have 4WD). Some cars, such as certain Subarus have ADW.

Is there a difference?

[Obie]

A 4WD has low range and is a a safer choice for coming back down from the summit.Keeps from overheating the brakes.

[Lee M-S]

a friend works up there.
He says that visitors often lose control of their vehicles and wind up blocking the road and/or being injured because:
a) their vehicles don't work right at high altitudes (the car gets really, really sluggish, and may stop altogether)
b) their brains don't work right at high altitudes (thinking gets really, really sluggish, and may stop altogether)
This is true of 2WD, 4WD, and AWD. Also of smart AND not-so-smart people.

I went up to the top once and fell asleep--that's a common response to the altitude, and good thing I wasn't driving. We stopped for a couple hours at the visitor center to acclimate, but it didn't prevent the effects.

It was summer, but really, really cold--wear sweats, socks, boots, jackets, hats.

Not exactly an answer to your question, I know, more like a suggestion to think carefully before you decide to go.

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[TomK]

A 4WD vehicle will split power and torque evenly between all the wheels (when 4WD is selected) whereas an AWD vehicle is a little smarter and will automatically adjust the torque to the wheels depending on which wheel has the best grip. As Obie pointed out, however, the real reason you want a 4WD vehicle is for driving down on the dirt road as you can select low-range and have the engine brake the car for you. There have been several accidents caused by visitors and residents burning their brakes out on the way down. Our organisation has several 4WD vehicles and one AWD car, but we never drive the AWD vehicle above Hale Pohaku. Incidentally, it's good practise to switch back to 2WD when on the paved road since when 4WD is selected all the wheels turn at the same speed which makes cornering a problem.

[Kelena]

Ah, okay -- the difference is that 4WD has a special low gear that allows you to use engine braking in descending so as to avoid burning out the brakes. Mahalo, Obie and TomK.

Lee M-S -- I have been up there twice and my reaction was the same each time.....I thought everything was very funny. I also was in slo-mo, but that might be attributable to the fact that I am eligible to apply for Social Security this coming year. Made it up the trail to the summit faster than my younger friends, though.

[jerry]

We had some people from New Zealand stay at our B&B and they took their 2wd to the top. Their response--"it was nothing--you should see our roads." Depends on what you are used to, I guess.

Jerry

[Midnight Rambler]

Also, especially now, bear in mind the possibility of ice and/or snow on the road. You really don't want to hit that on a hairpin turn coming down with poor traction.

[TomK]

The Mauna Kea Support Services rangers have become pretty strict in the last few years about closing the road when there's snow or ice on it, so it's unlikely you'll face driving in those conditions. Plenty of people drive up there in 2WD vehicles but I wouldn't recommend it. The condition of the dirt road has become quite bad in recent years because the traffic to the summit has increased quite significantly and there have been many occasions when I've driven up there that I was thankful I was in a 4WD vehicle. The other problem some might face is that rental car insurance in many cases won't cover you up there so if you have an accident or even a break down up there you could be facing some difficulties.

[terracore]

They have recently been studying ibuprofen's ability to prevent altitude sickness. It's an "off label" use of the drug but since it's available over the counter, easy enough to try.

http://med.stanford.edu/ism/2012/march/altitude.html