Economy Compacts Fare Poorly in Crash Tests
- December 19, 2006
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- Posted by George Peterson
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The Insurance Institute for Highway Safety has just released their first crash ratings for Economy Compact Cars. They call them “minicars”. The IIHS often releases results like this to pressure car makers to achieve higher safety results than are required by the Federal Government (NHTSA). Being part of the insurance industry, the IIHS charter is to provide information that consumers can use to select a safer car or light truck – and hence a car that might generate lower personal injury claims in an accident.
Force Still Equals Mass X Acceleration… F=MA
The first thing you learn in Physics 101 is F=MA. Basically, this equation means that something bigger is going to win if it hits something smaller. People have historically bought Lincoln Town Cars partly because they were so big that they were guaranteed a “win” in an accident. The same thinking goes with Large Sport Utility Vehicles like the Chevrolet Suburban.
A very small car is going to lose in an accident with a much larger vehicle. There will be much more physical damage to the small car than to the big one. And all things being equal, people riding in the small car are more at risk. The IIHS and Federal Government have noted that as fuel economy goes up (through vehicles getting lighter and smaller), damage and injuries also go up. In this case, bigger and heavier is better. But with skyrocketing gas prices folks rightly want more fuel efficient cars and trucks.
With that in mind, Economy Compacts have been introduced… Toyota Yaris, Honda Fit, Nissan Versa are the three that were launched in 2006 as 2007 model year cars. Only the larger Versa aced the crash tests… Versa includes side curtain air bags as standard equipment. Yaris, where side curtain air bags are optional, fails if it is not equipped with these safety enhancements.
The IIHS press release is included below the fold if you want to read the whole thing. But just remember, when it comes to safety, and all other things are equal, the bigger vehicle will win. F will always equal MA.
First crash tests of minicars: Nissan Versa earns the highest overall rating; three minicars earn poor ratings in side tests
ARLINGTON, VA – December 19, 2006 — For the first time, the Insurance Institute for Highway Safety has tested the smallest vehicles sold in the US market, which gain popularity as fuel prices rise. Now these cars are rated for comparison of occupant protection in front, side, and rear crashes. The Nissan Versa earns good ratings in all three tests. Two other cars earn good ratings in front and side but not rear tests.
Crash test results indicate which vehicles in each weight category afford the best protection in real-world crashes, and this round of tests reveals big differences among the smallest cars. But results of real crashes show that any car that’s very small and light isn’t the best choice in terms of safety. Driver death rates in minicars are higher than in any other vehicle category. They’re more than double the death rates in midsize and large cars.
“People traveling in small, light cars are at a disadvantage, especially when they collide with bigger, heavier vehicles. The laws of physics dictate this,” says Institute president Adrian Lund. Death rates in single-vehicle crashes also are higher in smaller vehicles than in bigger ones.
Minicars weigh about 2,500 pounds or less. A typical small car weighs about 300 additional pounds, and midsize cars weigh about 800 pounds more than a minicar. A midsize SUV weighs 4,000 pounds or more, exceeding the weight of a minicar by at least 60 percent. In every vehicle category (car, SUV, or pickup truck), the risk of crash death is higher in the smaller, lighter models.
“Despite the safety trade-off, more consumers are buying minicars,” Lund says. “This is why we tested them. We want consumers to use the ratings to choose the most crashworthy designs among the smallest cars.”
Versa is Best
Bigger than the other cars the Institute tested this time around, the Nissan Versa is classified a small car, the next size class up from minis. But this car is marketed to compete with minicars, so the Institute is releasing its ratings along with those of competing models.
The Versa is the only car in this round to earn the highest rating of good in all three tests. In the frontal test, its structure held up well, minimizing intrusion into the space around the driver dummy. Most injury measures were low. In the side test, the standard curtain-style airbags prevented contact between the striking barrier and the heads of the crash test dummies (Nissan is modifying the side airbags in cars built after November 2006 to improve protection in side impacts).
The Institute’s side test is especially challenging for small cars because the barrier that strikes the test vehicle represents the front end of a pickup truck or SUV. Side airbags designed for head protection are crucial because the barrier crashes into the side of the car right at the head level of the two dummies that are positioned in the driver seat and in the rear seat behind the driver.
“The Versa is bigger than the other cars we tested, so it has size and weight on its side as well as good test results,” Lund says.
The Honda Fit with standard side airbags and the Toyota Yaris equipped with optional side airbags also earn good ratings in front and side tests. However, rear protection isn’t rated good. The Yaris is rated marginal for occupant protection in rear impacts, and the Fit’s rear rating is poor.
The Institute conducted two frontal tests of the Fit. In the first test the frontal airbag deployed too early, allowing high forces on the driver dummy’s head. Honda is modifying the airbags in cars built after November 2006 and says it will recall cars built earlier. In the second test of a Fit with the design change, the frontal airbag deployed properly, and injury measures recorded on the dummy’s head were low. The published rating is for vehicles with the design change.
Side Tests Trip up Four Cars:
The Hyundai Accent, Scion xB, and the Toyota Yaris without its optional side airbags earn poor ratings in the side test. The Chevrolet Aveo is marginal. The Accent and Aveo didn’t perform well even though they have standard side airbags. The Aveo’s front seat-mounted side airbags did a good job of protecting the driver dummy’s head, but this car’s structural performance was marginal. Intrusion into the occupant compartment led to high forces on the driver dummy’s pelvis. There’s no side airbag protection for rear-seat passengers, and the barrier struck the dummy’s head.
The Accent’s structural performance in the side test also was marginal. Curtain-style airbags in front and rear seats provided good head protection, but measures recorded elsewhere on the driver dummy indicate a motorist in a similar real-world crash would be likely to sustain internal organ injuries, broken ribs, and a fractured pelvis.
Overall the Accent is the lowest rated car in this group. The rank order takes into account all three ratings (front, side, and rear).
Another poor performer in the side test is the Scion xB. Side airbags aren’t available, and the xB’s side structure didn’t do a good job of resisting intrusion during the impact. The barrier intruded into the car and struck the driver dummy’s head. Measures indicate the likelihood of brain injuries, serious neck injuries, and a fractured pelvis in a real-world crash of similar severity.
“The Scion’s poor side rating and marginal rating in the rear test are especially disappointing because this car is marketed to young drivers, who have the highest crash rates and thus the greatest need for crashworthy vehicles,” Lund says. “Toyota says it will replace the current xB design later in the 2007 model year, and hopefully the new version will be a better performer.”
People often choose to buy very light cars for fuel economy but “you don’t have to buy the smallest, lightest car to get one that’s easy on fuel consumption,” Lund points out. “Models including the Honda Civic, not even the hybrid version, and Toyota Corolla are bigger than the minicars we tested and weigh more, so we would expect better occupant protection in serious crashes. At the same time, these and other small car models get nearly as good fuel economy as minicars.”
Rear Protection Isn’t Keeping Pace
Cars have been earning good ratings in frontal crash tests for several years, and now improvements in side crash protection are accelerating. But the seat/head restraints in many cars still don’t provide adequate protection for most people in rear-end crashes. This is the case among the cars the Institute recently tested. Every model except the Versa, classified a small car, earns a low rating of marginal or poor.
“When a vehicle’s seat/head restraint design isn’t good, people are more likely to suffer neck injuries in rear impacts,” Lund points out. This is the most common crash type in commuter traffic. More than 2 million insurance claims are filed for whiplash each year, costing more than $8 billion. About 1 in 10 of these injuries results in long-term pain and/or disability.
How do the neck injuries occur? When a vehicle is struck in the rear and driven forward, its seats accelerate people’s torsos forward. Unsupported, an occupant’s head will lag behind the forward movement of the torso. This differential motion causes the neck to bend back and stretch. The higher the torso acceleration, the more sudden the motion, the higher the forces on the neck, and the more likely a neck injury is to occur. Seats and head restraints have to work in concert to support people’s necks and heads, accelerating them with the torso as the vehicle is driven forward. The head restraint has to be tall enough and close enough to the back of the head to catch it early in a crash, and the seat has to have some “give” to help keep the head and torso moving together.
“The seat/head restraint combinations in every car except the Versa that we tested this time around wouldn’t provide adequate protection against whiplash,” Lund says