Crash-test dummies are packing on the pounds to better reflect the expanding waistlines and larger rear ends of many Americans.

Manufacturer Humanetics has developed the new model after studies found that obese drivers are 78 percent more likely to die in a car crash.

Dummies have traditionally been modeled on a person weighing about 167 pounds with a healthy body mass index.

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Super size me! Dummies have traditionally been modeled on a person weighing about 167 pounds, left, but manufacturer Humanetics has developed a 273 pound model, right, to better reflect expanding waistlines

The new super-sized dummies are based on the measurements of a 273-pound person with a BMI of 35.

A BMI of over 30 is considered morbidly obese by the Centers for Disease Control and Prevention.

Seat belts, air bags and other safety features have all been designed for thinner people and don’t fit larger people in the same way, Chris O' Connor, CEO of Humanetics, told ABC.

‘Typically you want someone in a very tight position with their rear against the back of the seat and the seat belt tight to the pelvis,’ he said.

‘An obese person has more mass around midsection and a larger rear which pushes them out of position. They sit further forward and the belt does not grasp the pelvis as easily.’

A similar conclusion was reached in a 2010 study from the University at Buffalo and Erie County Medical Center.

Tight squeeze: Seat belts, air bags and other safety features have all traditionally been designed for thinner people and don’t fit larger people in the same way, according to Humanetics

The study, which analyzed data from more than 150,000 car crashes in the U.S. between 2000 to 2005, found that moderately obese drivers faced a 21 percent increased risk of death, and morbidly obese drivers faced a 56 percent increased risk of death.

‘Crash test dummies have saved lives and provided invaluable data on how human bodies react to crashes, but they are designed to represent normal-weight individuals,’ sais lead author Dr. Dietrich Jehle at the time.

With more than 70 percent of Americans now clashed as either overweight or obese, according to the CDC, O’Conner said the death risk for obese people in cars is a serious problem that must be addressed despite fatal accidents being at historic lows.

‘We need to find a way to make cars safer for everyone, regardless of size,’ he said.

The data used to create the new dummies also indicated that obese female drivers had double the risk of becoming a fatality compared with obese men.

The larger dummies are expected to become available to manufacturers for use in testing sometime next year.