What do you spend most of your money on? For most people, their two biggest expenses are their home and car(s). If you remember the post comparing expenses in 1913 to 2012, you might recall the three things that Mr. Average spent most of his “raise” on were:

• Housing (36 percent of the raise)
• Income taxes (28 percent), and
• Transportation (24 percent)

A majority of the increase in transportation has, arguably, to do with that wonderful instrument of freedom — the automobile.

The choices we make

Our spectrum of choice in cars is, of course, wider than a mile. Egotistas spend big on the latest model of the coolest car. Hollywood celebrities once flaunted their beblinged Cadillac Escalades at the annual Oscar ceremony. That was before the 2002 recession. When that hit, it suddenly wasn’t cool any more to be seen piloting a behemoth slurping down rivers of Mother Earth’s precious resources. That’s when the curtain went up on the eco-friendly Toyota Prius, which Cameron Diaz and other stars rode to the 2003 big event in their sipply little Priuses. Overnight, saving the planet with the Prius became California Cool.

That was then.

The top 1 percent, as we saw a few weeks ago, figured out a way to ensure that a full 95 percent of the wealth increase from this economic recovery gets channeled into their pockets. With that, concern for saving the planet went the way of Uggs for boys, and now the wheels of choice for gliding down Rodeo Drive has become a Range Rover, starting at $85,000 (new, of course).

While an egotista’s main concern is how to bling up a new Range Rover, the other end of the spectrum is occupied by frugalistas sporting boring robust-o-cars destined for at least ten more faithful years of service. Those road warriors are inevitably at least 20 years old, scored on Craigslist for $500 from people with more money than savings concern.

Most of us find ourselves somewhere in the middle of the bulge of the ever-present bell curve, seeking to save while driving something a tad less extreme. That includes the mythical Mr. Average, the darling of all statisticians and bloggers.

So what does Mr. Average spend to keep his or her car on the road? The three biggest car expenses are depreciation, fuel, and car insurance. How does Mr. Average try to save on these items? Buy a cheaper car, is the usual answer.

Not for insurance. You would think you would save on auto insurance with an economical Toyota Corolla, which would be cheaper to insure than, say, a Chevy Tahoe, which is approximately twice the cost. You would be wrong. In an actual comparative pricing study I did for another blog post, I discovered that insuring the more expensive Tahoe is actually cheaper in total dollars than insuring the economical Corolla (new, as well as used).

Comparing gas mileage and depreciation is relatively easy. Getting a handle on car insurance costs for Mr. Average, however, is not.

You see, car insurance is greatly affected by “other” factors than by your choice of vehicle. According to Insurance.com, there are four basic factors insurance companies use to set your rates, and the actual vehicle is only third on that list.

The biggest factor setting your auto insurance rate is you — or, to be more specific, how insurance companies see you. You are bound to hate some and love some of these distinctions, but they’re driven by hard data, collected and analyzed by geeks at their computers.

Who you are

Age: If you’re under 25, your car insurance rates will be higher. Over 25, it depends. It drops until you become seriously interested in Depends, at which time your car insurance rates will start to climb again.

Along with age, insurance companies look at how many years you’ve been driving. Statistics prove that people who have driven longer file fewer claims. For that reason, it usually pays to keep your driver’s license current, even if you live somewhere like New York City or Chicago, where you many times don’t even need to own a car or drive. (Of course, you may need to have a driver’s license in America to write checks or buy stuff with plastic. Foreigners sometimes have a hard time figuring out how being able to pass a driving test qualifies you to write checks, but that’s a different story.)

Gender: Women pay less because:

• They drive less
• They get in fewer accidents
• They get fewer speeding tickets
• They get fewer DUI convictions
• They buy safer cars

Please note: that’s not a personal judgment. Insurance companies agree that that’s what the numbers say.

Zip Code: Where you live affects your rates, because the frequency of “risk events” varies greatly from neighborhood to neighborhood. These risk events include vandalism, theft of cars and/or contents, and fraudulent claims. Again, these are not Mark Cuban types of assessments; they’re conclusions drawn from statistical data. For this reason, it’s not uncommon for two identical people living just a few miles apart to have a difference of as much as 50 percent in their auto insurance rates.

So, if you’re considering moving, it might be a good idea to find out what the difference will be in your car insurance. You can get quotes from esurance, Progressive, or other online insurance providers — or you can fill out a single form at Insurance.com and get free online quotes from a bunch of insurance companies any time you want to compare rates. (It’s pretty slick, but I digress.)

In general, it’s cheaper to insure cars in rural areas, because they have less crime, less traffic, and fewer accidents.

Credit History: You might not think paying your credit card bill late would increase your car insurance, but you would be mistaken. According to an insurance broker friend of mine, statistics show that people with bad credit file claims something like 40 percent more frequently than those with good credit. If you want to look into this, here’s an article about how and why your credit history affects your car insurance premiums.

Occupation: Again, statistics rule when it comes to insurance. Occupations like scientist, pilot, or actor/artist show lower claims and, therefore, have lower car insurance rates, generally speaking. Why? I want to say nobody really knows, but I’m sure somebody does. The most common explanation I’ve heard is that those occupations require attention to detail and being meticulous. In other words, those people are careful. That’s in contrast to occupations with high auto insurance rates, such as lawyers, business executives, judges and doctors. Apparently, the reason for that is the stress level that comes with jobs like those. (They say the rate for doctors isn’t much lower than for teens.) Real estate brokers also pay more because they have to drive more.

Marital Status: Did you know married people get into fewer accidents than their unmarried counterparts? Insurance companies do, and that’s why they offer married people lower rates. In addition, insuring two cars with the same company usually will get you an additional multi-policy discount, much like the next criterion.

Homeownership: Insurance companies generally charge less for homeowners because they’re regarded as more stable. By itself, that’s not a significant factor, but the discount you get from combining your home and car insurance is.

The rest

The other basic factors determining your auto insurance rates are:

• Your driving record (accidents, tickets, etc.) and claims history
• The coverage you’re looking for (pretty obvious)
• Your vehicle

The impact of your vehicle selection is not obvious, so it’s not simply that a more expensive car will carry a higher insurance premium. In fact, as pointed out above, a Tahoe costs less to insure than a Corolla.

Chances are that if you’re concerned with getting rich slowly, you will have a good (or at least improving) credit record, and you’ll be on the positive side of many of the variables listed above. But now you know exactly how those factors can lead to savings on your auto insurance, the third largest expense of car ownership.

How have you gone about lowering your car insurance premiums?