ego

You are convinced you are a better driver than most.

A 1981 study of student participants found that 93% of the U.S. sample rated their driving skills as being in the top 50%.

The original study surveyed a small sample of students, not the general population of U.S. drivers.

Your self-assessment assumes your peers are worse than they are.

Where this comes from

Study: Ola Svenson, 1981, Illusory Superiority
What the check found: The 93% figure is accurate to the Svenson study, but the study surveyed university students, not representative U.S. drivers.
Confidence: Well replicated

One of these every day, and every one names the study it came from. When a finding is contested, it says so.