wow, i go for dinner and we're on page four already?
Lc, 70 vs 70 is dramatically different than 80 vs 80. However, betelgeuse, 90 vs 50 is identical to 70 vs 70. Well, under the assumption that both are head on collsions. The total net total is 140 in both cases. I do agree that 40 vs 40 is more survivable than 70 vs 70. Although, even 40 vs 40 is the same as going 80 and hitting a stationary object (like a solid wall). Chances of walking away are limited at best.
I remember from one of the driving school courses (of many

) that a front end collision can be compared to falling off of a building. And for every ten miles an hour faster you go, it is the same as adding another story to your fall off of a building. In this case 40 vs 40 would be the same as driving your car off of an 8 story building.
The people in the Hummer had a hell of a better chance surviving because of Impulse of the forces. The Hummer weighs alot more, so the actual forces exerted on the people is considerably less.
As anyone who has ever hit something (another car, deer, wall, tree) head on can attest, at 10mph it wakes you up enough for you to say, "wow, that's alot of force". At 20mph you say to yourself, "man!". At 30mph, it friggin hurts. At 45mph, it happens so fast that you spend the next ten minutes trying to figure out what the hell happened and you thank whoever you believe in that you were wearing your seatbelt. Looking at those pictures, the kids in the MS3 never had a chance.