NEW YORK (CNN/Money) - Auto insurers in the United States and Britain are experimenting with programs that put electronic monitoring devices in customers' vehicles to track how they are driving, giving the drivers a chance to obtain lower insurance rates, according to a published report.

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USA Today reported Monday the tests are voluntary for customers of U.S. insurer Progressive, which will begin its trial in Minnesota on Aug. 24, and British insurer Norwich Union, which will start its test in a few weeks.

The Progressive test puts a device in the car about the size of a box of Tic Tacs that keeps track of speed, how many miles are driven and at what time of day. Every few months the customer can take it out of the vehicle, download the data into a computer, and if he or she wants to share it with the insurer, send it to Progressive online.

Those drivers who go over Minnesota's 75 mph speed limit less than 0.1 percent of the time will get a 5 percent discount. Those who avoid driving at the most dangerous time -- between midnight and 4 a.m. on weekends, also get a discount.

Those who don't send in their data are not penalized, they just don't get the available discounts.

The Norwich Union test involves a global positioning satellite to track where the vehicle is, constantly sending information to the insurer. Cars that spend more time in safer areas will qualify for larger discounts.

Progressive tried a similar test using GPS devices in 2001, but dropped it due to high costs and privacy concerns of customers who didn't want their location constantly monitored, the paper reported.