Under federal regulations, vehicles are required to include a latch that opens the truck from the inside.
To test the latch in the 2013 Lexus ES 350, automotive test director Jake Fisher instructed his 4-year-old son to climb into the trunk and test the latch, the Los Angeles Times reported Saturday.
After his son climbed in, Fisher closed the trunk and when his son tried the lever to open it up, the latch broke.
"My 4-year-old's small hands snapped off the lever that opens the lid. He was not able to escape from the trunk until I opened it from the outside," Fisher said.
Consumer Reports said it advised federal regulators and Toyota, which produces the Lexus, of the problem.
In turn, the National Highway Traffic Safety Administration said it was already investigating the problem and was "evaluating available information to determine if additional action is warranted."
Toyota said it would look into the problem.
The Times said the issue involved the 2013 Lexus ES and GS.