NHTSA: Convertibles can’t share standards with fixed-roof vehicles
By Rick Kranz and Harry Stoffer
Automotive News / November 07, 2005
Roof-crush proposalNHTSA proposes to upgrade its standard for roof-crush resistance for the first time since 1971. Key provisions are
- Increase the applied force in testing to 2½ times each vehicle’s unloaded weight, up from 1½ times in the current standard.
- Add a requirement for maintenance of enough headroom to accommodate a mid-sized adult male occupant.
- Extend the roof-crush resistance rule to vans, trucks and buses with a gross vehicle weight of 6,000 to 10,000 lbs.
- Clarify the definition and scope of exclusion of convertibles.
Federal regulators want stronger vehicle roofs to protect people in rollover crashes, but they have no plan to protect occupants of convertibles.
The National Highway Traffic Safety Administration says it cannot hold convertibles, including retractable hardtops, to the same roof-crush requirements as vehicles with fixed roofs. The agency also has decided against convertible-specific rollover rules, such as requiring roll bars.
There has been a sharp increase in convertible offerings in the past decade, and existing roof-strength rules exempt convertibles. Several import automakers have added rollover safety equipment voluntarily. Although concern has mounted over rollover deaths in SUVs, convertible rollover deaths are a nonissue for NHTSA, the insurance industry and some automakers. The 94 fatalities attributed to 87 convertibles that rolled over in 2004 accounted for fewer than 1 percent of about 10,000 U.S. rollover deaths last year.
"We’ve been asked the convertible question many times, and we don’t see a higher pattern of injury losses," said Kim Hazelbaker, senior vice president of the Highway Loss Data Institute, a research organization for auto insurers.
Safety lobbyists and regulators say convertibles’ low center of gravity makes them less prone to rollover.
NHTSA’s proposed overhaul of its standard for "roof-crush resistance" will require increased roof strength for most vehicles. The rules are an effort to reduce fatalities and serious injuries in rollovers. They are primarily aimed at vehicles with a high center of gravity such as SUVs and pickups.
The agency is accepting comments until Nov. 21 for the new standard, the first revision since 1971. As proposed, the standard will cover vehicles — except convertibles — with a gross vehicle weight of 10,000 pounds or less. The rule would take effect no earlier than the 2010 model year.
Although federal rules do not affect convertibles, German and Swedish automakers have taken the lead in protecting convertible occupants in a rollover. While there is no vehicle standard in Europe regarding occupant protection in convertibles, European automakers have been proactive over the past 15 years.
They have addressed the rollover issue on two fronts. First, they have strengthened the A-pillars and windshield frame to withstand a rollover.
Second, they have engineered one of two different roll bar systems into the rear of the passenger compartment:
1. Stationary roll bars
2. Mechanically or electrically operated hoop-style roll bars that pop up when the system senses a potential rollover.
The roll bars are positioned behind the front seat in two-passenger convertibles and behind the rear seats in four-passenger convertibles. The top of the bar can in some cases be 10 inches above the headrest.
The roll bars would not meet the new rollover standards. But automakers offering them say they offer some protection.
Volkswagen began offering roll bars in its convertible in 1980. Mercedes-Benz followed in the 1990 model year. Audi, BMW, Porsche, Saab, Volkswagen and Volvo offer such protection, as does Honda in the S2000 roadster.
One analyst believes other automakers who make convertibles should follow their lead.
"This may be one of the times where the OEMs should take the lead and say this is the right thing to do," said Michael Robinet, vice president for global forecast services of CSM Worldwide in Farmington Hills, Mich., referring to automakers that fail to offer roll bars.
Convertibles without roll bars include the Toyota Solara, Chrysler Sebring, Ford Mustang, Chevrolet Corvette, Pontiac Solstice and Lexus SC 430.
Chrysler’s PT Cruiser has a "sport bar" positioned above the passenger compartment, but it is there to provide structural integrity, not rollover protection. The Nissan 350Z and Mazda MX-5 Miata appear to offer roll bar hoops, but they are not engineered to provide protection in a rollover.
"It is not something that we can legally call a roll bar," says Jeremy Barnes, a spokesman for Mazda North America Operations. "They are two structures that sort of look like roll hoops behind the driver and passenger’s head. They do add to the structural integrity of the vehicle, but they are not there specifically to protect the driver and passenger’s head in the event of a rollover."
A spokesman for Nissan North America offered a similar response.
Not too pricey
Such rollover safety equipment is not tied to premium-priced vehicles. The least expensive of these European convertibles is the base 2006 Volkswagen New Beetle convertible, which stickers for $22,535 including shipping. That four-passenger vehicle features mechanically operated hoops behind the rear seats that automatically pop up when the vehicle senses a rollover.
"It is something that we think is a selling point for the car," said Tony Fouladpour, a spokesman for Volkswagen of America. "It is something that we think the customer of a German-built car expects, a little bit extra, especially in the area of safety."
Intuitively, convertibles look less safe in a rollover. But they are less likely to be involved in rollovers, says Hazelbaker of the Highway Loss Data Institute.
Aside from their low center of gravity, convertibles often are extra vehicles in a household, used only on weekends and rarely taken out in bad weather, he says.
So, for insurers, "from a risk standpoint, that’s pretty good business," Hazelbaker says.
NHTSA intends to keep testing for roof strength by pressing a heavy metal plate on the top of a vehicle directly behind the A-pillar. Under the NHTSA proposal, the roof must resist a force equal to 2Â½ times the vehicle weight. The current standard is 1Â½ times vehicle weight.
No traditional convertible can meet either the current or proposed standard. Federal law says that NHTSA cannot regulate a vehicle type out of existence, says NHTSA spokesman Rae Tyson. That means it cannot apply the standard to convertibles.
A growing range of vehicles — convertibles with a retractable hardtop — will be treated as convertibles by NHTSA. That means they would be exempt from the proposed roof-crush standard. The reason is that the A- and B-pillars are not permanently connected. Among the vehicles that would be exempted are the Cadillac XLR; Mercedes-Benz CLK, SLK and SL; Volvo C70; and Pontiac G6 due early next year.
Gerald Donaldson, senior research director for Advocates for Highway and Auto Safety, says his organization has never urged rollover protection in convertibles because it never had a good opportunity — until now.
The organization, a coalition of consumer groups and insurers, is analyzing the roof-crush proposal but has not decided on its response, Donaldson says. But simply requiring roll bars for convertibles would probably not be sufficient because occupants’ heads would likely still hit the ground, he says.
Alan Shapey, a New York lawyer who has handled rollover cases, has sent highly critical comments to NHTSA criticizing the roof-crush proposal.
Shapey said convertible rollovers have not been a hot topic because they occur infrequently. But he supports convertible-specific rollover regulation such as permanent or pop-up roll bars.