WASHINGTON — Many motorists don’t know it, but it’s likely that every time they get behind the wheel, there’s a snitch along for the ride.

The National Highway Traffic Safety Administration on Friday proposed long-delayed regulations requiring auto manufacturers to include event data recorders – better known as “black boxes” – in all new cars and light trucks beginning Sept. 1, 2014. But the agency is behind the curve. Automakers have been quietly tucking the devices, which automatically record the actions of drivers and the responses of their vehicles in a continuous information loop, into most new cars for years.

When a car is involved in a crash or when its airbags deploy, inputs from the vehicle’s sensors during the 5 to 10 seconds before impact are automatically preserved. That’s usually enough to record how fast the car was traveling and whether the driver applied the brake, was steering erratically or had a seat belt on.

The idea is to gather information that can help investigators determine the causes of accidents. But privacy advocates say government regulators and automakers are spreading an intrusive technology without policies to prevent misuse of the information collected.

Data collected by the recorders is increasingly showing up in lawsuits, criminal cases and high-profile accidents. Massachusetts Lt. Gov. Timothy Murray initially said that he wasn’t speeding and that he was wearing his seat belt when he crashed a government-owned car last year. But the Ford Crown Victoria’s data recorder told a different story: It showed the car was traveling more than 100 mph and Murray wasn’t belted in.

There’s no opt-out. It’s extremely difficult for car owners to disable the recorders.