car size and crash safety
The size of your car plays a key role in an accident. Bigger cars, trucks, and SUVs generally fare better than smaller cars, especially when there's a collision between big and small.
As a prospective car buyer, you might see fuel efficiency as the most important value you look for in a car, and this could lead to greater interest in smaller cars. But what if that compact efficiency comes at the cost of safety? The truth is that size and weight are incredibly important. And while a smaller car might do well in crash tests against other cars in its own genre, those results may not translate in crashes with bigger cars. If nothing else, it's something to consider when shopping for a new car and comparing crash test results.
Smaller cars could put you at greater risk
When experts evaluate safety, a car's size and weight factor into the testing criteria in addition to the structural strength and material. These are important contributors to what's known as a vehicle's crashworthiness (no matter how technologically advanced a vehicle is). We'll explain why.
Size matters for front ends and passenger protection
In a frontal collision, the front end is the part of the car that bears the most impact. A bigger front end gives a car more time to absorb the impact, slowing the car as the front end gets crushed. This reduces the force on the front-seat passengers and lessens the chance of intrusion into the passenger area. In general, the more distance between a car's front end and its passengers, the safer those passengers will be in the event of a front-end collision.
Smaller cars, with their smaller front ends, transfer more of a collision's impact to their passengers, which can increase the risk of injury.
Smaller cars tend to weigh less, and lighter cars fare worse in a crash
Lighter cars don't do as well against heavier cars in crashes.
A heavier car has greater momentum and requires more energy to slow down than a lighter car. In a crash, passengers in a lighter car will experience more of the collision's force than passengers in a heavier car, which can also increase the risk of injury.
So if a big, beefy Escalade (at over 5,000 pounds) crashes into a small car like a Ford Focus (under 3,000), the driver in the Escalade has a better chance of walking away unscathed thanks to the Escalade's bulk.
Smaller cars have higher fatality rates in car accidents
The Insurance Institute for Highway Safety (IIHS) explains that while cars of all types are much safer now than before, the smallest and lightest cars have fatality rates around twice as high as the biggest and heaviest cars. When you consider how car size and weight impact a vehicle's crashworthiness, it's easier to understand why small cars don't do as well at protecting their passengers.
Crash tests haven't always told the whole story
Just because your car performed well in a crash test doesn't necessarily mean you'll be well protected in an accident. In fact, testing how well a car protects you in a collision with a larger car is a relatively recent idea. Previous tests monitored how well a car performed in a crash against a car of similar size and weight — an unlikely event on the road.
In 2009, the IIHS conducted a car size and safety experiment. They crashed a Honda Fit (minicar) into a Honda Accord (midsize car); a Smart Fortwo (2-seat city car) into a Mercedes C class (compact); and a Toyota Yaris (subcompact) into a Toyota Camry (midsize car).
In each crash, the bigger car fared better.
Another tidbit worth mentioning is that each of the "losing" cars fared well in more traditional crash tests, which typically involve crashing into a barrier at 40 mph. But when they hit a bigger moving object, the results were less reassuring.
Weighing the pros and cons of car size and safety
There are plenty of reasons to buy a small car, including fuel efficiency, affordability, maneuverability, parkability, and adorability. If you choose to go the smaller route, keep in mind that you're at greater physical danger when driving around bigger and longer cars and trucks.
But if safety's a "must have" on your list, you may want to look for a bigger car that protects its cargo in crashes with smaller cars.
The good news for eco-conscious drivers is that smaller cars aren't necessarily the most fuel efficient anymore. Green cars like the surprisingly heavy Nissan LEAF are making it easier to find a car that saves at the pump and can keep you safer in an accident.
And remember: not all small cars are created equal. Check out the IIHS's annual list of top safety picks to research a make and model you've got your eye on.
The IIHS report on car size and crash safety
Read the PDF detailing the '09 study.