A new survey finds most drivers have not changed their auto insurance carrier for the last 12 years.  

(Gunnar Pippel, ThinkStock)

In fact, the survey from InsuranceQuotes.com found millennials and senior citizens were most likely keep the same auto insurance for a decade or more. Senior Analyst Laura Adams, however, says drivers should check competing premiums at least once a year.

"The time of year that you shop really doesn't matter.  We are seeing that a lot of the drivers, in fact one in four has been with the same company for more than 16 years," Adams said.

The survey also showed 7 percent have been with the same carrier for more than 30 years.

Are there rewards for that kind of loyalty? Adams said in some cases they may be.

"There are some companies that do offer loyalty for sticking around and being a longtime customer," she said.

She said in many cases, you have to be with them at least three years and up to five years before those discounts kick in. Adams also said that depending on the type of policies that you have, bundling coverage for different things -- such as auto, home, renter's insurance, etc. -- could result in a discount.

So why are millennials taking the same route as seniors and sticking with the same auto insurer?

"It could be that the millennials are really just beginning their sort of relationship with insurance, they are new with it," Adams said. "They don't really understand that the marketplace is always changing. Rates are never going to be the same."

Adams said that in some cases, "shopping around and getting policies from different companies can actually mean a net premium that's going to be lower than sticking with the same company."

"When you are looking around for auto insurance, it can be as much as 200 or 300 dollars per year in savings that you can find by switching companies," she said. "The quote that you got last year is not going to be the same quote that you get this year."

Adams recommends that drivers include getting new quotes on their calendars each year.

"Make a routine, and get in the habit of checking in to shop around all of your insurance policies," she said. "And it is just a really good shopping habit to get into."