And Senate leaders say the study lends credence to their efforts to kill a bill that would repeal the one-year-old cards.

The driving privilege cards were designed to allow undocumented immigrants to legally buy car insurance and get behind the wheel, but stop them from using it as official ID for government purposes, such as participating in elections.

Opponents of last-year's legislation creating the cards - namely advocates for Utah's growing Latino community - warned that immigrants would be wary of signing up for the cards, which would single them out as illegal.

But the audit showed the state's driver license division has issued 25,000 driving privilege cards and that most of the recipients also had valid insurance.

The auditor's office, acting on the request of Sen. Curt Bramble, R-Provo, studied a sample of 2,500 holders of driving privilege cards and found that three out of four had insurance. That rate was only slightly smaller than among those who have the standard-issue driver license.

A similar look at 2,500 licensed Utah drivers found that 81 percent had insurance.

Senate President John Valentine said the auditor's examination shows "the driving privilege card is working."

He urged legislators to reject HB64, a bill attempting to repeal the cards by the end of this year.

Rep. Glenn Donnelson, R-North Ogden, says undocumented immigrants should have no legal right to drive.

Legislators have yet to debate HB64.

mcanham@sltrib.com