Federal safety officials are unveiling new, tougher crash test standards today for 2011 model year vehicles.
Some of the major changes to the rating system include the use of a female-sized crash test dummy. For the first time, the Department of Transportation is using these smaller-sized dummies to help determine how well a vehicle protects in accidents.
"We've raised the bars on safety. More stars safer cars. People really have to prove to us these cars deserve a 5-star rating," said Secretary of Transportation Ray LaHood.
Cars will get safety ratings of 1 to 5 stars -- with 5 stars as the highest score.
Consumers can use the ratings to help analyze how well the vehicle protects in the front, side and rollover accidents.
The new tests, along with the new ratings, include a side crash into a pole and front and side impacts with not just male dummies, but with females too.
"In the past only male dummies were used and we know that obviously a lot of women are passengers or drivers in those cars," LaHood said.
But the use of female-sized dummies in crash tests is nothing new.
The Insurance Institute for Highway Safety has used female dummies in side crash tests since 2003 after research showed women could be more vulnerable in these accidents.
"Smaller people have their seats further forward -- that tends to put their heads right in the middle of the window. There's nothing between their heads and whatever is coming in from outside," said Adrian Lund with the Insurance Institute for Highway Safety, a non-profit group funded by auto insurance companies.
He called the government new tests, "A step in the right direction."
The government's new rating system may have automakers scrambling again. Only two of the 34 vehicles rated so far received a top rating of 5 stars.
The Nissan Versa ranked last with 2 stars and the top-selling Toyota Camry earned only 3 -- down from top ratings with the old tests.
"This is caused by the new testing procedures, not because the vehicle is less safe," according to Toyota officials.
Nissan did not respond to a request from ABC News for comment about the Versa's poor showing.
One other change: For the first time automakers will be required to put a vehicle's star rating on a sticker on a new car's window. That will allow consumers who are shopping for cars to see how the car did in the government safety tests.
For more information about the new crash 5-star safety rating system, visit: National Highway Traffic Safety Administration.