Do some research and you'll find the size of a car is a minor factor in overall safety.
I think you've got the facts very wrong (I hate to be abrupt, but facts are important here)
The crash test programs (e.g. the very good program run by IIHS) almost always compare vehicles in the same weight class. That is because weight is such an important over-riding factor in crash performance (especially against vehicles of different mass) that it would overwhelm most differences caused by good vehicle design, etc.
There are two reasons:
Momentum--you can't repeal this with engineering. If a 4000# chunk crumpleable steel going 60 mph hits a 2000# chunk of crumpleable steel 60 mph head-on (assume a perfectly inelastic collision) , they both end up going the same direction as the 4000# chunk was going, but at 20 mph. In the very brief time of the collision, which chunk endured the bigger acceleration: the chunk that changed velocity by 40 MPH or the one which changed velocity by 80 MPH? Which block would you rather ride in/on?
Space: Heavier cars tend to be more voluminous as well, offering more crush space and crushable structure. Given the same degree of good engineering, that reduces the chances of object intrusion into the passenger compartment and also greatly reduces deceleration forces.
Yes, good engineering and designing for crashworthiness is very important, but weight is also a huge factor.
From the experts:
Weight Matters, Vehicle Weight, weight class
Weight Class - Statistics show that if two vehicles with the same
NHTSA full frontal rating crash into each other head on, but one vehicle weighs twice as much as the other, the occupants of the lighter one (2000 lbs / 909 kgs) are eight times more likely to be killed than the occupants of the heavier vehicle (4000 lbs / 1818 kgs). However, vehicle weight offers no safety advantage or disadvantage in single-vehicle crashes.
Question from figner:
When I see stats that compare accident/injury/death rates for different types of cars, I wonder how much is correlation vs causation. To take a hypothetical example, if MINI drivers have the same rate of death per distance driven as a larger car, how much of that is due to the type of person who buys a MINI vs the larger car? Does anyone have a link to some stats or articles which try to take this sort of thing into account?
From (derivative source) :
Seatbelt Physics
"The U S Department of Transportation keeps data on traffic accidents including the Fatal Accident Reporting System (FARS) with fatalities since 1975 which number over a half million (averaging 45,000 per year in the US). Each year there are about 18 million property damage crashes with 1.7 million injuries. The risk of accidents for young drivers is greater in all categories of accidents, 18 yr olds having 400% more accidents than 40 yr olds. Analysis of such data permits reasonable estimation of factors which influence safety such as
vehicle mass and the
use of seatbelts. Some interesting human factors come into play. For example, given a severe crash, the driver of a 900 kg car is about 2.6 times more likely to be killed than the driver of an 1800 kg car. But overall data indicates that 1.7 times as many drivers of 900 kg cars are killed, compared to 1800 kg cars, indicating that drivers of light cars are more cautious and less likely to have such accidents. In seatbelt statistics, it must be factored in that persons who choose not to use seatbelts are more likely to have accidents out of a higher general bent toward risk taking.
