The National Highway Traffic Safety Admin. is expected deliver a new roof-crush standard April 30.

The proposed rule calls for vehicle roofs to withstand at least 2.5 times a vehicle’s weight, a 67% increase over the current standard of 1.5. Part of a comprehensive initiative to reduce rollover fatalities and injuries, the proposed rule supplements a federal mandate that requires all new vehicles be equipped with electronic stability control by ‘12.

Meanwhile, Hyundai Motor America cites stability control’s rollover-mitigation properties in defense of the Hyundai Tucson’s poor performance in roof-crush ratings recently released by the Insurance Institute for Highway Safety. The Tucson cross/utility vehicle received the lowest IIHS rating, along with platform-mate Kia Sportage.

“ESC is standard on all Tucson, a claim that others who finished higher in the IIHS testing can’t make,” says Hyundai’s Jim Trainor, adding the vehicle “meets or exceeds” existing government roof-crush standards.

The IIHS results are the first from its new roof-crush test. To earn a “good” rating, the top score, the vehicle’s roof must withstand a force of four times the vehicle’s weight before it collapses 5 ins. (12.7 cm).

Vehicles deemed “acceptable” must withstand 3.25 times their weight, while a “marginal” rating is assigned to vehicles that withstand 2.5 times their weight. The IIHS considers “poor” any vehicle that collapses 5 ins. when less than 2.5 times its weight is applied to its roof.

Just four of the 12 small CUVs the organization tested received “good” IIHS ratings – the Volkswagen Tiguan, Subaru Forester, Honda Element and Jeep Patriot.

The Suzuki Grand Vitara, Chevy Equinox/Pontiac Torrent, Toyota RAV4, Nissan Rogue and Mitsubishi Outlander earned the next-best score of acceptable, while the Honda CR-V and Ford Escape/Mercury Mariner/Mazda Tribute triplets provided marginal protection, according to the IIHS.

The organization argues the government hasn’t done enough to encourage stronger roof standards.

“If government rulemaking rested solely on science, there would have been an upgraded roof crush standard decades ago,” IIHS President Adrian Lund says. “Instead, the process has been bogged down by politics and indecision.”

The proposed rule dates back to a 2005 mandate issued by the Bush Admin.

In its original form, testing was limited to driver’s side roof crush. Following public consultation, the rule was revised to also evaluate performance on the front passenger side.

The approval process was further delayed by the White House transition from the Bush Admin. to the Obama Admin.