Snapshot records the time of day and speed per second one drives. However, Progressive says that it does not use speed to calculate the discount. Instead, it uses the time of day and speed to calculate the number of miles a customer drives, as well as how often the driver slams on the brakes.

The device also confirms the Vehicle Identification Number, the time and date that the device is plugged in and the percentage of time the device is connected.

Snapshot is about the size of a garage door opener and plugs into the on-board diagnostic port. After 30 days of driving with the device, customers can check to see if their driving style has earned them a discount.

As part of the program, drivers leave the device in their cars for six months. At that point, Progressive says it will recalculate a renewal discount and customers will then return the device.

For example, Snapshot does not have GPS. Thus, Progressive doesn’t know where the car is. Pratt says that although the device originally contained GPS, that function was removed as customers complained about a possible lack of privacy.