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.

In the next few days, the National Highway Traffic Safety Administration is expected to propose long-delayed regulations requiring auto manufacturers to include event data recorders — better known as “black boxes” — in all new cars and light trucks. 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 things like 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 cause of accidents and lead to safer vehicles. But privacy advocates say government regulators and automakers are spreading an intrusive technology without first putting in place policies to prevent misuse of the information collected