Take pity on the 20-year-old single man who buys auto insurance.
A new study by InsuranceQuotes.com shows someone in this group will pay far higher monthly premiums than a single woman his age, a married man his age—and dramatically more than a married man who is just five years older.
"Across the board, you see young men paying more for insurance, which makes sense," said Mike Barry, spokesman for the Insurance Information Institute. "Statistically, young men are riskier drivers, which means they are, on average, more expensive to insure."
How much more expensive?
A 20-year-old single man pays 49 percent more for car insurance than a 25-year-old single man.
Read MoreInstant insurance claims—apps for your car crash
He will also pay 23 percent more than a 20-year-old single woman, according to the study.
"It's not until they get some experience under their belts—and have a clean driving record—that rates start to drop," Barry said.
While it's well known that auto insurance premiums tend to drop as people get older and become more experienced drivers, there are other factors that bring rates down.
Read MoreThe $500K fender bender in London's luxury quarter
For example, 20-year-old single men pay 24 percent more for auto insurance than 20-year-old men who are married.
InsuranceQuotes.com says a 20-year-old single woman will pay 28 percent more than a woman the same age who is married.
Why?
"It's based on the assumption that individuals—particularly young individuals—get more serious about being better drivers when they're married," said Bob Hunter, former commissioner at the Texas Department of Insurance and current director of insurance at the Washington-based Consumer Federation of America, a consumer advocacy organization. "It's questionable, but insurers maintain that claims data back it up."
The study shows the gap in auto insurance premiums for married and unmarried drivers narrows as people age—that is, until they turn 60.
The InsuranceQuotes.com study found monthly premiums stabilize around age 30, and then steadily decrease for men and woman until they turn 60. After that, they start to edge higher.
Read MoreDriving violations drive up insurance, study shows
Even then, a 60-year-old single male driver is paying, on average, 60 percent less for auto insurance than a 20-year-old single man. For women, the difference is an average of 50 percent less.
As always, how many tickets a person collects—and certainly, how many accidents and claims they file—will push their premiums higher regardless of age, gender or marital status.
—By CNBC's Phil LeBeau.
Questions? Comments? BehindTheWheel@cnbc.com.