According to the National Drivers Test, administered by GMAC insurance last month, one in five motorists – roughly 38 million Americans – are unfit to drive on our nation’s highways.

The insurance company asked motorists from all 50 states and the District of Columbia 20 questions from their local DMV’s written driving test. The average score was only 76.2 percent, and about 20 percent of currently licensed drivers would have failed the test.

Of all states, New York drivers ranked last, for the second year in a row, with an average score of 70 percent. New Jersey motorists followed their neighbor state with a 70.5 percent. Kansas drivers, with an 82.3 percent average score, ranked highest. Idaho and Wisconsin tied for first last year.

According to Wade Bontrager, senior vice president of marketing at GMAC, in an article for BusinessWeek, it is pretty typical for areas with large urban populations to do poorly. This is because the areas tend to be more congested and fast paced.

Male drivers scored better than females on both average scores (78.1 percent male versus 74.4 percent female) and failure rates (24 percent female versus 18.1 percent male). In addition, other results showed that the older the driver, the higher the score.

One scary statistic: about 25 participants admitted to driving while talking on mobile phones, eating and adjusting the radio or selecting songs on an iPod. However, only 5 percent of participants reported texting while driving.