A new study by the insurance industry found that millions of licensed Americans lack a basic understanding of road safety.

The inaugural GMAC Insurance National Drivers Test, sponsored by GMAC Insurance, found that of the 5,000 licensed drivers studied, many did not understand common and safe procedures for merging, yielding when making left turns and road-sign interpretation.

According to the study, one in 10 drivers – close to 20 million people – would fail a state driver’s test if it were given to them today. Based on answers to a 20-question test, the survey sponsors concluded that drivers between the ages of 18 and 24 are most likely to fail actual state driving tests, while drivers between 50 and 64 are most likely to pass.

Other frightening responses showed that 1 out of 5 drivers did not know that a pedestrian has the right of way at both marked and unmarked crosswalks; 1 in 3 drivers sped up to make it through a yellow light even when pedestrians were in the crosswalk; and 50 percent of all drivers said they did not know how to merge into heavy traffic.

Driving while under the influence was also a concern in the study. Twenty-nine percent of the respondents admitted to driving over the legal limit “if they felt okay.”