Shocking as that may be, it's actually an improvement. Last year, 38 million received failing grades. Nationwide, the average score this year increased to 77.9% from 76.2% in 2010.
According to GMAC Insurance, which conducted the survey, the results mean that a great number of people on the road still lack basic driving knowledge, an ignorance that leads to dangerous driving habits.
For example, a full 85% of those surveyed could not identify the correct action to take when approaching a steady yellow traffic light.
And only one in four knew safe following distances.
But, the survey suggests, you can avoid some of these drivers if you know what to look for: Young people, women and motorists who live in the Northeast.
Twenty-seven percent of women failed the test, while males had a failure rate of 13.6%. The oldest drivers tested -- ages 60 to 65 -- had the highest average test scores at 80.3%.
Drivers in the Northeast scored lowest, while respondents in the Midwest fared best. The worst place, no surprise to anyone who drives there, is Washington, D.C.
Wyoming, where less than 5% of the population failed the test, took home the top prize for states.
The annual GMAC Insurance National Drivers test polled 5,130 licensed drivers from 50 states and the District of Columbia with a 20-question test derived from state department of motor vehicles exams.