Last week, Insure.com released a list claiming to reveal the most and least expensive states in which to insure your car. Instead of naming the usual suspects, states like New Jersey and New York, that tend to dominate these kinds of lists, Insure.com has Louisiana in its number one slot. Followed by Michigan. And then... um, Oklahoma?

In fact, the East Coast didn't even make the top five, with the top eastern “state,” Washington, D.C., coming in at number seven. New Jersey and New York ranked just 22nd and 23rd, respectively. The list got a few state insurance agencies -- and AOL Autos -- wondering.

"I got calls from a few states," said Amy Danise, the managing editor of Insure.com, "wondering why they had jumped a few places. I said because we were looking at where insurance was most expensive, not what people were buying."

Those few words explain the revelations behind Insure.com's list.

Rankings of insurance costs from bodies such as the National Association of Insurance Commissioners (NAIC), where you'll find the usual major metropolises in the top spots, are what Danise intended to counter with the Insure.com ranking.

Most Expensive States For Car Insurance

StateAverage Premium
1. Louisiana$2,510.87
2. Michigan$2,098.29
3. Oklahoma$1,869.39
4. Montana$1,857.96
5. California$1,774.41

Source: Insure.com, from a study commissioned by Insure.com from Quadrant Information Services

"People look at the NAIC rankings," said Danise, "and don't realize that they're actually ranking what insurance people buy, not what people pay. For example, if people in Montana drive older cars and don't get high coverages because there aren't that many people around and liabilities aren't as great, then they'll purchase relatively less insurance compared to someone in New York. That drives down your expenditures. The NAIC list actually tells you where people are buying more or less insurance."

In this example, if the tendency is for people to purchase less coverage in Montana than in New York, a comparison of how much people are paying will make it appear as though insurance is less expensive in Montana, when that’s not necessarily be the case.

Insure.com's approach wanted to find out how much would it cost a single driver to buy the same coverage in each state. So they started with a pedigree for a sample customer, "a 40-year-old single male driver who commutes 12 miles to work." Another important point that will come up later: Insure.com’s hypothetical customer has good credit.

The next step was to create a sample policy, with limits set at $100,000 for injury liability for one person, $300,000 for all injuries, and $50,000 for property damage per accident. Deductible on collision and comprehensive was set at $500 and the policy included uninsured motorist coverage.

Least Expensive States For Car Insurance

StateAverage Premium
1. Maine$902.85
2. Vermont$968.58
3. Ohio$999.86
4. Wisconsin$1,010.93
5. New Hampshire$1,011.23

Source: Insure.com, from a study commissioned by Insure.com from Quadrant Information Services

Then Insure.com chose the insurance carriers whose rates it would test: State Farm, Farmers, Progressive, Allstate, Geico, and Nationwide.

The rates for the hypothetical buyer for 2,400 different cars were processed through those six agencies in ten different zip codes in each state. If you’re thinking that ten is an awfully tiny number compared to the total number of codes in each state, you’re right. Louisiana, for instance, has more than 700 zip codes. Yet, there was a method.

"The cars," said Danise, "from a Porsche to a Mazda Tribute, but excluding exotics like Lamborghinis, represent the average of the universe of 2010 vehicles. For the zip codes, [we] used census data, and took the two largest and two smallest, by population, and then six with populations in the middle."

The premium cost for each state was a final average of all the rates collected, with Louisiana taking “top honors” for being almost $1,100 more expensive than the national average for an annual premium. Insure.com laid out one of the regulatory reasons for the spendy rates there: A $50,000 threshold for jury trials leads to a lot of settlements around that amount, which everyone in the state pays for with their higher premiums.

After the list was clarified for us, we were still curious: If you live in an expensive state, are you just doomed to pay more unless you move? Thankfully, the answer is a resounding “not exactly.”

We spoke to Alan Wiesenhahn of Wiesenhahn Insurance Agency in Land O’ Lakes, Florida, about how rates are determined. He stressed that insurance is such a personal affair that your rates might not demonstrate the same relative cost from state-to-state that Insure.com's list indicates.

"A carrier could have 250 different factors for deciding how much to charge you," he said, "and not even agents will know them all. But lists like this are difficult to judge because there are companies that are looking at your credit as the first factor when deciding what your rate should be."

Remember when we said Insure.com's buyer had good credit? This is why that's important. If you don't have good credit and you're looking for insurance, getting a quote from a carrier that uses your Experian number as a first test can blow your premium into another corner of the galaxy for reasons you weren't expecting.

"Other factors," said Wiesenhahn, "might not even have anything to do with you. We're in a somewhat rural area, but our rates are relatively high for where we are because there are only two roads in and two roads out. That means more traffic and more chances for accidents. That's a factor. There's a carrier here selling policies with lower premiums in order to increase market share. That has nothing to do with you, but it will affect what you pay."?

When it comes to buying car insurance, the only way to know what you'll really pay is to get actual quotes to cover your vehicles with the coverage you want. Every state has an insurance oversight department, and Louisiana's has put together a list of sample rates for an 18-year-old driver in 14 different cities. For the same driver, Automobile Club Family Insurance Company quotes about $2,016 for six months, while Hallmark Insurance quotes $5,189 for the same period.

?As incessant television commercials will attest, a little time with a car insurance comparison-shopping tool can swing your premiums in big ways, both up and down. But at least you can put off moving to Maine, the cheapest state on Insure.com’s list, for a little while longer.