There's no question that crumple zones and design are a vary important factor. I just disagreed with the statement that mass has no effect.
The crash test you cite does nothing to disprove the effects of mass in a collision, for the same reason the Galaxy vs Civic comparison is bogus. You're comparing a pickup truck, which doesn't have to be built to the same safety standards as cars, to a sedan from a company with a focus on safety (notice that the same organization recognized the Forrester as the safest small SUV).
I didn't that small agile cars are unsafe (I drive one after all, without a roof or roll bar at that), but I think it's wrong not to acknowledge that low mass carries a liability in a collision with another vehicle. You should recognize the weaknesses as well as the strengths if you want to accurately evaluate the safety of a car.
I'm sure that the Elise will be a safe car. I just don't think that it will be as safe as an Accord.
2005 S2000 #42as