The Jeep Wrangler received the US Insurance Institute for Highway Safety's lowest score in its latest round of crash tests.
Volkswagen's Tiguan, Mitsubishi's Outlander and the Jeep Patriot were also tested alongsidetheFord Escape, Nissan Rogue, Mercury Mariner, Mazda Tribute, Chevrolet Equinox and Pontiac Torrent.
IIHS president Adrian Lund said the Escape, Tiguan, Outlander and Rogue were equipped with standard electronic stability control and side air bags, and said the safety equipment helped the vehiclesshow significant improvements in safety.
"This is a huge change from just five years ago, when most small SUVs were rated either marginal or poor in our side test, and standard side air bags and electronic stability control were rare," Lund said.
However, the two-door Jeep Wrangler, tested without optional side airbags, received a "poor" scoring, the institute's lowest score.
Lund said that during the latest test, the Wrangler's driver door opened during the crash, which could lead to a person being ejected from the vehicle.
A Chrysler spokesman said the Wrangler complied with federal safety standards and that "no single crash test provides a full picture of a vehicle's crashworthiness."
Earlier versions of the SUV subjected to the same tests received "marginal" scores in side crash tests.
Tests of the Jeep Patriot were conducted both with and without side airbags.
The model equipped with the optional airbag received the top score in the side test, while the one without the side airbag received the second lowest score. Both models received "acceptable" scores in front-end tests.