The following is a guest post by John Egan.

When it’s time to go shopping for a new or new-to-you car, you probably figure your budget carefully so you’ll know just how much you can spend each month to slip into the driver’s seat.

But there’s an important figure that many of us forget to add to our vehicle cost estimates — what we’ll have to pay to insure our new rides.

The Insurance Information Institute tells us that insurance companies consider many factors when they’re determining auto insurance premiums. They’ll look at your driving record, your age, where you’ll drive the car and how much you’ll drive it.

But the kind of car you pick also can make a big difference. Insurers take into account how much you paid for the car, how likely it is to be stolen, how much it costs to repair and the car’s overall safety record. In general, you’ll pay lower premiums on a car that’s at the top of the safety rating chart than you would for a comparable vehicle with a less-than-favorable safety rating.

Fortunately, it’s fairly easy to find out which vehicles are likely to cause the least insurance premium pain. Each year, the Insurance Institute for Highway Safety (IIHS) checks out the safety of new vehicles by measuring their performance in high-speed crash tests (front and side) and in rollover tests. They also evaluate how well the seats’ head restraints prevent neck injuries in rear impacts.

Once all the test numbers are in, the IIHS announces its top safety picks for the year. The nonprofit institute divides its picks into 12 categories, including mini-cars and compacts, sedans, minivans, SUVs and pickup trucks. Be sure to check out this list if you’re looking for a car that will be safer to drive and less expensive to insure.

Shopping for a used car? You’re in luck. The IIHS data goes back to 1994.

Suppose you know you want a certain type of car — say a midsize SUV — but aren’t sure which model to choose. The IIHS website will let you compare the safety records of different models within each vehicle category.

For an estimate of how much it might cost to insure a particular vehicle, check out Edmunds.com’s True Cost to Own calculator. Simply enter a vehicle’s make, model, year and style, and this calculator will figure out roughly what you’ll need to spend on the car — including insurance premiums — over the next one to five years.

The results might surprise you. If you’re looking at 2012 four-door sedans, for example, Edmunds.com says the Toyota Camry will cost you about $9,668 in insurance premiums over five years, while you’ll pay $9,497 to insure a similar Honda Accord. But take a look at the 2012 Hyundai Sonata — its estimated insurance bill for five years adds up to $8,880. That difference of several hundred dollars could translate into a car payment or two.

Of course, there’s another really easy way to get an estimate of what your new car will just to insure: Visit an auto insurance comparison website or contact an auto insurance company or agent. They can calculate — based on information about you, your car and your driving record — how much you’d have to pay to insure specific makes and models.

John Egan is managing editor of the website autoinsurancequotes.com, which provides online car insurance news and services to consumers in all 50 states. John’s goal is to deliver high-quality content and auto insurance tips to drivers so they can make informed decisions about choices that affect their pocketbooks and their driving experience.