"The temperatures can go up to 40 to 50 degrees higher than the outside temperature and you know I can tell you at 106 or 107, a baby will die," said Janette Fennell, president and founder of Kidsandcars.org.
Fennell warned even the most responsible parent can make this deadly mistake.
"This can and does happen to anyone, so look before you lock," she said.
Fennell also suggests placing your cellphone or your handbag on the backseat to remind you to open the back door. But Fennell said enhanced technology is the best way to prevent these tragedies.
That's similar to what CBS News found at a Kia dealership in New Jersey.
Although this type of technology already exists in some vehicles, safety advocates said the auto industry has been resistant to change. But Congress is now working on what's called the Hot Cars Act, which would standardize the technology in most new automobiles.