The Insurance Institute for Highway Safety has named five minivan models Top Safety Picks for 2011, recognizing their higher safety in the event of rollover crashes.

The 2012 Chrysler Town & Country, Dodge Grand Caravan, Volkswagen Routan, Honda Odyssey and Toyota Sienna each demonstrated superior safety, according to IIHS. The first three models share a common structure, so it is not surprising that they were found to have comparable safety. The Nissan Quest had an acceptable rating.

Rollover protection was determined by pushing a metal plate against one corner of a vehicle's roof at a constant speed, since roof strength is the key factor. The 2012 models of the Town & Country, Grand Caravan and Routan have improved their roof strength, so earlier models will not provide the same protection.

"Safety-conscious parents shopping for a family hauler should be pleased with today's minivan choices," said IIHS chief research officer David Zuby.

Top Safety Picks must demonstrate good safety in front, side and rear collisions, as well as rollover crashes. Among other factors, testing accounts for the way a passenger's head is supported and protected by using a dummy to measure force on the neck. Safer vehicles commonly have lower car insurance rates along with other benefits.