Again, saying the laws of physics still apply is meaningless, obvious, and trite. People often say that in regards to weight because it sounds clever. However, there is a lot more to the physical properties of a crash than simply vehicle weight.
And again, you're over simplifying the statistics and making some bad conclusions. It’s not your fault, a lot of government agencies have as well. For that many outside groups have challenged the worth of some of these studies, and some have even accused gov regulatory agencies of bowing to pressure by US automakers and those they lobby in congress. Wouldn’t be the first time, CAFE standards being a prime example.
Fundamental to any statistical study is the premise that correlation doesn’t establish causation. That brings to mind the old saying: lies, damn lies, and statistics.
The first statement is “Important characteristics of vehicles that
influence their driver death rates are type, body style, size, and weight.” Notice weight is only one factor out of four they listed, and I’d add price/trim to the list.
For example, it states that light 2-door vehicles had a high incidence of death. First off, is the Prius a 2-door? No. Secondly, 2-door vehicles are typically smaller, which mean they have less space to accelerate passengers in accidents, so there is the size issue. Is the Prius small? No, it’s a typical sedan size. Is the Prius cheap or skimpy on safety? No. There is also a higher percentage of sports cars, convertibles, and such high risk vehicles in the light 2-door category. Were those factors controlled out in the study to insure apples/apples comparisons?
In regards to the Camry or toher similar sedans which are slightly heavier: is that additional weight in any way safety related, or is it things like greater luxury? Who knows, but without knowing comparisons are meaningless.
Also, it states the lightest SUV were more prone to deaths. That’s an odd choice of words. Why doesn’t it say “there is a continuum across all car makes when comparing equal levels of trim, type, size, and body style, where percentage of death directly correlates with weight of vehicle and scales proportionately across the spectrum of weight.” That would be more compelling than highlighting the “lightest” SUV and 2-door vehicles, which are outliers by definition. Always be leery of any statistics citing outliers.
In the extreme categories they chose to mention, there are many cheap “lifestyle” vehicles often marketed as sportier, driven faster, and with less safety features (or luxuries or anything else that increases cost) specifically because they’re “lifestyle” vehicles not “practical” vehicles. Take the small light Suzuki Samurai for example. That’s one of the lightest SUV and I bet it’s a death trap, but not due to weight. It's unsafe because it's "cheap and sporty" design doesn't even have proper doors or a roof, is very narrow, and basically lacks any consideration for safety. And there are a lot of similar vehicles in that category, but there are some safe practical minded ones too. I would say many 2 door vehicles are lighter, and also either sportier or cheaper, and hence less safe. That doesn’t mean a practical, small, light, 2 door vehicle can’t be safe by design though, just that they’re often not designed to be.
So, does that really indicate lightness increases death, or is it just reading into rather meaningless statistics with prejudice? I would say cheaper vehicles are generally less safe, because safety and good design are costs. Also, many cheap vehicles are also light, because less safety and luxuries may also reduce weight. That doesn’t mean all lighter vehicles are less safe. Volvo for example is designing the “Safety Concept Car” and it’s a moderately light and small 4-door hatchback on the Prius scale.
The bottom line is that safety is more a feature of design than anything else. An informed consumer should look at cars on an individual basis, and not make assumptions based on such popular myths about weight which can be totally misleading.
Having said that, SUV and Trucks are extremely difficult to make stable and overcome the rollover problem, even with the best design. A truly wide/squat vehicle like the Hummer is an exception because it is so wide. But most all SUV produced have much higher center of mass combined with the approximate width of an ordinary car, and are going to be less stable as a result.
Also, high bumper SUV with high center of mass and large wheels tend to leap upwards in accidents, which has two effects: 1) it tends to crush the cabins of other vehicles, including other SUV and trucks, 2) they tend to roll over more as a esult of departure from the pavement; both of which increase injuries and fatalities for the passengers of both vehicles.
Truly the stupid vehicles of choice.