Of all the cars on the road, which ones do the best job of curbing whiplash (search) risk when hit from behind?

Certain models of Volvo, Saab, Jaguar S-Type, Subaru Impreza, and Volkswagen New Beetle fit the bill, according to the nonprofit Insurance Institute for Highway Safety.

The IIHS recently examined a wide range of late-model cars from various makers, paying special attention to seat/head restraint combinations, which can protect from whiplash injury from rear end crashes.

First, experts rated 97 seat/head restraint combinations available in 88 car models sold in the U.S.

Strategic seat/head restraint geometry can help prevent whiplash by keeping the head and torso aligned, reducing the risk of the head snapping forward and then jerking back in a rear-impact accident.

Next, 63 cars with 73 good or adequate seat/head geometry ratings were smashed into from behind, with crash-test dummies to show whiplash danger. The test simulated a parked car being rear-ended by a vehicle of the same weight going 20 miles per hour.

Only eight of the 73 seat/head restraints earned an overall “good” rating on crash testing, 16 gained an acceptable score, and 19 earned ratings that were marginal. In alphabetical order, those cars which scored a "good" rating were:

—Jaguar S-Type: 2005 models, all seats

—Saab 9-2X: 2005 models, all seats made after September 2004, active head restraints

—Saab 9-3: 2005 models, all seats, active head restraints

—Subaru Impreza: 2005 models, all seats made after September 2004, active head restraints

—Volkswagen New Beetle: 2004-05 models, seats with adjustable lumbar, active head restraints

—Volvo S40: 2004-05 models, all seats made after February 2004

—Volvo S60: 2003-05 models, all seats

—Volvo S80: 2003-05 models, all seats

However, 30 seat/head restraint combinations were rated “poor” in the crash tests, and 24 seat/head restraint combinations flunked the geometry test, disqualifying them from the crash test and automatically earning a “poor” rating.

“Good geometry is a simple and necessary first step toward adequate protection, and seats with bad geometry cannot begin to protect many taller occupants,” says IIHS chief operating officer Adrian Lund, in a news release.

Neck injuries cost at least $7 billion per year in insurance claims, according to the IIHS.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Insurance Institute for Highway Safety, “Dynamically Tested Seat/Head Restraints,” Nov. 14, 2004. Insurance Institute for Highway Safety, “Seat/Head Restraints Not Dynamically Tested Because of Inadequate Geometry.” News release, Insurance Institute for Highway Safety. Associated Press.