That's probably true of most of em, but not me, I've been offroad in mine several times, nothing hardcore, but a 2WD without chains would have been in a world of hurt!! I went down one stretch of single track that I should have used the DAC, but my 59yr old memory forgot about it!!
I go down a steep grade on loose soil to get to a buddies cottage. I tried DAC and it is quite the technology. A lot of whirring and lights flashing but it works like a charm. I'm sure it helps keep the driveway in better shape too. Lights are to tell you its using the brakes and I think the whirring is actually using engine braking but I'm not sure. I use it every time now. Kind of tough to not hold your foot right by the brake though...
I find the uphill assist feature a lot more useful than the downhill one since I dont do much off roading. I remember in the old days, a auto transmission never goes backward when starting from a stop going uphill, wonder what happen to that?
Haven't tried it on my RAV, but had it on my old Landrover Freelander and used it a couple of times - more out of interest than need. That worked a treat.
The Freelander introduced hill descent control 10 years ago so I'd imagine the technology is in it's second or third generation. I have no reason to suspect the Toyota implimentation will be any less effective than Landrover's.
I tried it a couple days ago and I'm not sure, but I do think it provided some sort of alternate braking.
I was coming down a very steep road in the steep hilly area of Somerset here in Bellevue, WA and decided to hit the DAC button.
I also compared going down part of the road with it off.
With the DAC on, the DAC light flashes on your dash; no real audible sounds loud enough (unfortunately on this test I had the radio on); feet still has to be on the brake and had to still apply a good amount of pressure to prevent accelerating.
With the DAC off, it was my perception that the vehicle accelerated much quicker and a greater brake pressure input was needed to keep the speed down.
It'll flash when on, but not when engaged. Did you drop it into 1st gear? You would notice it working immediatly after taking your foot off the break (since it works with low gearing and rpm).
If you stop while it's on, and put the car into a higher gear, the DAC will continue to flash until you turn it off.
Tried DAC last week while at my cottage. Photo doesn't do justice to the grade. DAC was amazing. Went down the grade and around some sharp turns in the loose gravel with no problems. The brakes could be heard and felt pulsing on and off during the decent.
My parents live in the Somerset area of bellevue and I seem to use it once a year or so around there house when we actually have a good amount of snow on the ground. It's actually pretty amazing how well it works to safely take you down a low traction steep grade. you just have to steer, braking disengages it.