People who drive fewer than 15,000 miles per year can save 13-54% on their GMAC insurance premiums under a GMAC Insurance’s new Low-Mileage Discount. All you have to do is opt-in to let OnStar monitor your mileage. The average annual vehicle mileage is about 12,000 miles, according to the Department of Energy’s Annual Energy Review ’06, so it looks like most people with GMAC insurance and OnStar could save under OnStar’s Low-Mileage Discount Program. With the need to save every dollar on your car, this could be a good program for eligible drivers to check out by calling 1-800-GMAC-123 or going to gmacinsurance.com.