Very long post ...
As I've said many a time, I think the MDX is, overall, a very safe vehicle. In my personal opinion, I think the M-class is a notch above in safety, and I think the new Volvo XC90 will even exceed the M-class by another notch (just like I think the next-gen M-class due in 2004 will leapfrog the Volvo).
It comes down to not which is the safest vehicle, but which combination of safety and other vehicle attributes fits a buyer's priorities. Again, no SUV wars here please, but everyone likes and dislikes other attributes of all the aforementioned vehicles.
It may sound strange to not buy the safest vehicle out there, but we don't hide in our homes either. One could argue that if maximum safety was the requirement, perhaps one shouldn't even buy an SUV because of the their natural predisposition to roll over more readily than most sedans. Though one thing the anti-SUV lobby misses is that the higher riding position of most SUV's actually protects the SUV's occupants significantly in side-impact collisions.
It is always difficult to assess safety on paper, in the absence of scientific testing. And even scientific testing can be somewhat misleading (e.g. can one readily trust a manufacturer's statements about its internal testing?). That said, comparative testing is certainly better than unsubstantiated claims and even anecdotal crash info if it isn't in sufficient quantity and if the details about the crash are not fully verified.
It is definitely true that Volvo and Mercedes-Benz have consistently demonstrated the highest commitment to safety, and have been very innovative and have "overengineered" safety in to their vehicles. I have a mixed view of the overengineering because while much of the safety reputation is well-deserved, there's some aggressive marketing behind it and things can be deceiving -- aggressive claims from the manufacturers, and from some overzealous loyalists (as is true with all vehicles). E.g. stability control is definitely beneficial but it can't defy the laws of physics. It simply raises the vehicle's capabilities, but not to absolute heights. I cringe when I see comments that "these teenagers might be alive if their vehicle/that vehicle had ..." because it's much too speculative. I think their vehicles are generally safer, but they're not the last word in safety, which is why their research and the research of others continues.
It's also hard to know when a claimed advantage of a vehicle is realistic and will provide safety in all situations, and whether the competitors lack such features. E.g. it is true that some vehicles have had the front seats snap and go backwards in collisions, killing the occupant (often a child) behind them. However, whether or not the RX300, MDX, etc. have this issue is unknown, at least until some anecdotal crash information is available. One would hope that Acura has recognized the limitation of some of the older vehicles that may have had this problem, and addressed this with the MDX.
(Honda/Acura itself has made nice strides in safety, with their recent vehicles doing much better in crash tests than previous models. However, Honda/Acura has been slow with a number of safety innovations, e.g. better-designed headrests to prevent whiplash, stability control, and head-protection airbags. Indeed, i think Toyota/Lexus is somewhat ahead of Honda/Acura in this vein, making side curtain airbags available in even a Camry, achieving great crash test results earlier -- Camry vs. Accord in this example -- and making VSC available on many of its vehicles -- all SUV's but the RAV4, the Camry.)
Another example of possibly-overstated safety engineering are the vaunted patented door latches on the MB's that prevent the door from popping open in the accident. Despite this long-standing safety enhancement, the driver's door of a 1997 E420 opened in an IIHS crash test. Fluke? Overrated feature? Can one really know? Who can you trust?
Citation:
http://www.iihs.org/vehicle_ratings/ce/html/97005.htm
(please note this is a previous generation E-class, but I understand it had that door latch design)
Another example is the European crash test of the C-class, which has tremendous safety in a smaller package. Despite this, the European testers felt that the side curtain airbags (not that you can get these in an MDX, mind you) didn't deploy fully and could fail to prevent injuries in all cases. See:
http://www.euroncap.com/details.php3?id=merc_cclass_2001
Yet another example is the fact that initially the M-class did not come with child safety locks or true childseat top tether anchors. However, MB has nicely corrected this, and earlier M-classes can be retrofitted. Having a correctable safety deficit is much better than a non-correctable one.
And then there's the Volvo S40 which didn't quite get the highest rating in its recent crash test. See:
http://www.iihs.org/vehicle_ratings/ce/html/0124.htm
But, as Volvo points out, the S40 has a ton of safety features that other vehicles don't have. That's why it's hard to judge safety. Crash tests don't do it alone, though they are important.
And that's where I think Volvo and MB shine. I don't think they own a monopoly on safety, and I don't think that their vehicles represent absolute safety. E.g. I think MB needs to put better ergonomics in their vehicle to lessen driver distraction. But I think that overall they pack more safety technology into their vehicles (sometimes at the expense of other things) than other manfacturers. The M-class and the upcoming XC90 have things like side curtain airbags (though I think their benefit in higher-riding SUV's isn't as strong as they are with sedans), pretensioners in most if not all seating positions, rear side airbags (on the M-class; somewhat controversial when children are involved, up to the parent to decide), bi-xenon headlamps, and of course reinforced roof supports.
All MB's are subjected to factory rollover testing, of two different types, I believe. This is the famous "Stayin' Alive" M-class commercial where there is a brief clip of an M-class being rolled over.
http://www.off-road.com/mbenz/Staying_Alive.avi
Now, is this irrefutable proof of rollover resistance? Not irrefutable, I think, but I think it's a strong indication. I'd like to see Acura issue similar video. I understand that Lexus tried to copy the "Stayin' Alive" commercial but couldn't show the rollover test. Given anecdotal RX300 rollover stories and photos, I think one can guess why.
I don't doubt that a manufacturer can doctor video results, though. E.g. remember those old Volvo commercials where a vehicle was driven over the roofs of Volvos, and the roofs didn't crush? Then the scandal that broke when it was revealed that Volvo had reinforced the roofs to film the commercial, because the roofs were crushing?
However, I highly doubt MB would fake something like that with so much attention focused on rollovers and the suspicions from the Volvo-doctored video.
In a way, I hope I don't see any Acura MDX rollover photos or video, because regardless of whether the roof stands up to a rollover or not, a rollover's not a good thing for the occupants.
