Let’s say you’re in the market for auto insurance. You’re a savvy consumer, so you’ve shopped around a bit, looking at different policies. You’ve compared quotes from several insurers and weighed your options carefully.

And now that you’re finally ready to purchase... the policy is more expensive than you remember. Maybe a lot more expensive. You frantically search around, but that first quote is gone. So now you’re facing an unpleasant choice: Either shell out more money than you planned to spend, or go back to square one and start the search all over again.

It’s a deeply frustrating scenario - and a shockingly common one. What’s going on here? Why is it so hard to find reliable auto insurance quotes?

There are three big answers to this question. We’ll walk through them in detail, below. But here’s a little good news upfront: You can get real, trustworthy insurance quotes if you just learn the common problems - and how to avoid them.

Problem One: Many consumers don’t know their needs

Car insurance laws are regulated at the state level. That means the kind of auto insurance you need depends on where you live.

In some states, you only need to have liability insurance. These policies cover both bodily injury or property damage after an accident. But in some states, you’re also required to cover any healthcare costs you might incur with an insurance policy called a personal injury protection plan.

Some states even require uninsured motorist policies, which protect you in case of accident with someone who’s not properly insured. And finally, there’s collision insurance and comprehensive car insurance. These policies can help cover damages to your car from accidents, vandalism, hail, etc., and are always optional. There are even a couple states where no insurance is required (though skipping it may not be a great idea).

So what does all this mean for you, the consumer? It simply means that shopping for car insurance is confusing. If you get a quote for a liability insurance policy, but then it turns out you also need a personal injury protection plan, you’re in for an unpleasant surprise. The cost difference might be very large.

The solution to this problem is to know your insurance needs upfront. There are plenty of online resources which break down the kind of coverage you need on a state-by-state level.

Problem Two: Data moves quickly

In the old days, getting an auto insurance quote was a low-tech affair. You’d meet with an insurance agent, who would look up your details in a ratings book. They’d do some math and make you a quote on the spot, which you could take or leave.

Like everything else, this industry has been turned upside-down by digital technology. Today, when you get a car insurance quote online, your information is run through sophisticated software, driven by complex algorithms. These algorithms are constantly refreshed with the latest available data about accidents, automobile safety profiles, demographic information, and more. And all of that data can change overnight.

Let’s take an example. Say you get a quote from a car insurance company on Wednesday. But on Thursday, the latest nationwide accident data comes in - and it shows a spike in accidents among people who drive your model of truck. For the auto insurance company, this means that you’re at greater risk, so your quote goes up. They might also raise their quote if you enter a slightly more accident-prone age bracket. Or if your credit report shows a slight dip. Or if the economy wobbles, spiking all of their prices.

These fluctuations aren’t necessarily common events. A quote you receive today might not change for weeks. But in the information era, there’s simply no way to be sure. The solution, of course, is to act quickly. If you see a great quote, take it! It might not be there tomorrow.

Problem Three: Consumers don’t share all their details

This is a big one. When you’re punching your background data into a online auto insurance quote service, you might be tempted to cut corners. After all, there’s a lot of questions to answer - about yourself, your household, your history, your automobile, etc. But here’s the thing: All of these questions matter.

For instance, maybe you don’t bother specifying your marital status when you’re getting an auto insurance quote. Why would it matter? Well, it turns out that married drivers get in fewer accidents than single drivers - so checking that one little box could actually lower your rate.

Or you might enter the make and model of your car, but skip the vehicle identification number (VIN) because you don’t have it handy. No big deal, right? Actually, the VIN can raise or lower your rates significantly.

And perhaps you forget to mention that fender-bender you were in a few years back. You weren’t at fault, so it shouldn’t affect your rates - right? Unfortunately, it does put you in a higher risk category, mathematically speaking, even if you weren’t at fault. When the insurance company runs a background check and learns about your accident, they may raise your quote significantly.

The solution to this problem is obvious: If you want a reliable quote, you have to share as much accurate information as possible.

The Bottom Line

Getting a real, reliable car insurance quote can be tricky - but that’s largely because most consumers don’t understand the way these quotes are generated. But with a little background knowledge, you can dramatically cut down on these ugly little surprises, so you end up paying what you expect.

Some issues are out of your control, like the speed at which data travels in the 21st century. Changes in national accident data or insurance ratings can increase your quote overnight. The only solution here is to move quickly and pounce on a good deal when you see it. And fortunately, the more common issues are within your control - and you can take active steps to prevent them.

First, that means you should get informed before you start comparing quotes. Figure out what kind of insurance coverage you need, so you can make an apples-to-apples comparison. And second, remember that all of the background information you provide about yourself is crucial. Make sure you share thorough and completely accurate details, and your quote will almost certainly be the same when you’re ready to purchase.