Roughly 4 in 5 motorists fail to ask their car insurance company about qualifying for special discounts that insurers don’t automatically apply, according to a study commissioned by Denver-based insuranceQuotes.com.

Drivers typically get many discounts without asking, such as those for buying multiple policies from the same company or remaining accident free.

But motorists are required to request some breaks, including discounts for driving fewer miles than average; being married; working in jobs such as teaching, nursing, accounting and law enforcement; being a good student; and completing a defensive driving course.

For people who qualify, the discounts can be substantial. Someone who drives 5,000 miles annually pays an average of 8 percent less than someone who drives 15,000 per year, the study found. Marriage discounts are highest for young adults, with a married 20-year-old paying 21 percent less than a single 20-year-old. The gap narrows to 7 percent at age 25 and to around 2 percent after age 30.

Insurers also offer discounts for people in certain occupations: for high school and college students who maintain a “B” average; and for motorists who complete a defensive driving course. Studies have shown those types of drivers have fewer accidents, said Laura Adams, senior analyst at insuranceQuotes.com.

She recommends policyholders ask about special discounts at least once a year.