Documents show that General Motors recalled some Pontiac G6 midsize cars to fix a faulty brake light system in 2009, yet waited more than five years to call back over 2 million other cars with the same system.
It didn't recall newer G6s or the Chevrolet Malibu and Saturn Aura until three weeks ago.
The cars are nearly identical.
GM says the problem has caused 13 accidents and 2 injuries.
GM says the problem occurred less frequently in those cars.