PHOENIX - Want a big break on your auto insurance bill? All you have to do is give up some information to your insurance company about how you drive.

Drivers just plug in a device to track how often they drive, what time of day, and even how often they apply the brakes.

"In essence starts to allow you to see if this person drives like the average driver or if they drive better than that," says Richard Hutchinson, from Progressive Auto Insurance.

The voluntary program is called Snapshot, and drivers can earn discounts of up to 30 percent. It does not track drivers' locations.

Progressive is calling it usage-based insurance -- setting your auto-insurance rates based on your driving behavior.

Snapshot has been available in several states for a few years, and recently started up in Arizona.

Ron Williams at the Arizona Insurance Council says usage-based insurance is part of a trend. "If they can find new ways and new technologies to bring products and services to the people here in Arizona, they will do that," he says.

Progressive says it will not use the device to raise your rates.