Results from the 2009 GMAC Insurance National Drivers Test found that 20.1 percent of licensed Americans - amounting to roughly 41 million drivers on the road - would not pass a written drivers test exam if taken today.

But, the survey found that with age comes wisdom: The older the driver, the higher the test score. Drivers 35 years old and older were most likely to pass. The age group with the highest failure rates was young adults – aged 18 to 24. White males older than 45 received the highest average score.

Idaho and Wisconsin replaced Kansas's 2008 ranking as most knowledgeable; New York replaced New Jersey's 2008 ranking as least knowledgeable.

In addition to the 20-question DMV exam, GMAC Insurance posed subsequent questions exploring participants' planned driving habits for the following year and their take on mileage-based auto insurance programs known as pay-as-you-drive insurance. These findings revealed that ninety-three percent of respondents had never heard of a "pay as you go insurance" pricing model for automobile insurance but, once they found out what it was, one in three said they would enroll in a pay as you go insurance program if their insurance company offered one.