Way to go, NJ

When faced with a written test, similar to ones given to beginning drivers applying for licenses, one in ten drivers couldn't get a passing score, according to a study commissioned by GMAC Insurance.

The GMAC Insurance National Driver's Test found that nearly 20 million Americans, or about 1 in 10 drivers, would fail a state driver's test if they had to take one today. GMAC Insurance is part of General Motors' finance subsidiary, GMAC.

More than 5,000 licensed drivers between the ages of 16 and 65 were administered a 20-question written test designed to measure basic knowledge about traffic laws and safety. They were also surveyed about their general driving habits.

Drivers in the Northeast and mid-Atlantic states did worst. Twenty percent of test-takers failed there.

The state of Rhode Island leads the nation in driver cluelessness, according to the survey. The average test score there was 77, just eight points above a failing grade.

Those in neighboring Massachusetts were second worst and New Jersey, third worst.