This year's top selections are vehicles that earned the highest crash-test ratings in four categories; a frontal-offset crash test at 40 mph, a side-impact test that mimics a collision with an SUV or pickup truck, a rollover roof-strength test, and a rear-impact evaluation test, institute spokesman Russ Rader said.

Vehicles are then categorized as good, acceptable, marginal or poor, based on their test performances. Each of this year's picks was rated "good" in all four categories. The Fiat  500 (pictured above) was among the top-four picks in the mini category.

Of the 29 top-rated mini and small cars, 20 of them cost $20,000 or less. The new numbers  indicate continuing demand for safe but affordable small cars, Rader said.

Rader expects such a trend to continue in the future.  "Automakers are really focusing on safety because they know it's a selling point and they know that consumers are paying attention to safety," he said. "No automaker wants to be seen as behind the curve in crash-test safety."

Although compact cars are safer than ever before, "the laws of physics still apply," Rader warned. "Even though these small cars are top crash-test performers, it doesn't mean they are just as safe as bigger vehicles with the same rating."