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(ISeeCars) – When you’re out shopping for a used car, nothing is for certain. Behind the nice paintwork and detailing job is a car that has endured the use and abuse of previous owners – and there’s no guarantee it was as pampered as it might appear. A car can hide many secrets, and even the most fastidious inspection or test drive might not reveal serious red flags. 

This is where the vehicle history report comes in. There’s two major players proffering these reports: AutoCheck and Carfax (not to be confused with the used-car dealer Carmax). Each can give you an idea of a car’s past, but they aren’t identical. To paint a better picture of what these reports are, how they differ, and what other reports might be out there, we’ve done some digging and found some answers. 

Vehicle History Report: What is it, anyway?

Essentially, a vehicle history report is a car’s rap sheet: everything that might have happened to a car gets captured by these reports. ‘Everything’ refers to any incident that may have triggered some sort of insurance or DMV involvement. Examples of triggering events include ownership changes, reported accidents, if a car was deemed a lemon or was stolen, and any title changes to branded, salvage, rebuilt, etc.

These reports use the vehicle identification number (the VIN number) and massive databases of information to piece together an abridged record of a car’s past from before you found it on a used car lot. A clean report brings the sort of peace of mind you’ll want when buying something as pricey as a used car.

Carfax: the Standard

“Show me the Carfax” may have been first used as the Carfax slogan, but it has since seeped into daily speech. Much like Google and Kleenex in their respective fields, ‘Carfax’ has become a catch-all term for any vehicle history report. This didn’t happen by chance – of all the reports out there, Carfax is the most tenured, having been around in one form or another since 1986. Today, the company pulls data from over 100,000 sources and has over 17 billion records.

Carfax sifts through its trove of data to find theft records, flood damage history, accident indicators such as deployed airbags, and title changes related to a specific VIN number. It will tell you how many previous owners the car has had, if the odometer reading is verifiably correct, if there’s a loan or lien against the car, and if it has a clean title or was ever deemed a total loss. 

Unique to Carfax service history data as well as safety and emission inspection history. If a car ever failed an inspection, the report calls that out, along with when it failed and the mileage at the failure date. 

The service record history shows what maintenance was done and when. This information, however, might not be complete if an owner worked on the car themselves or took it to an independent garage that did not record what was done in a way that a Carfax database could find it. Nonetheless, it can give a good baseline as to the car’s general reliability and upkeep. 

If you buy a car with a clean Carfax but later learn that there was an issue in the car’s history recorded by the DMV but not picked up by the report, you’re entitled to a buyback guarantee. Carfax will buy the car from you for the full purchase price.

AutoCheck: the ratings-based report

One drawback to the Carfax report is that it gives you no basis as to whether the disclosed data is good or bad compared to similar cars; it’s on you to judge the significance of the information presented. AutoCheck, which is owned by the credit report giant Experian, seeks to remedy that with its score-based report. AutoCheck looks at many of the same factors Carfax does, but goes a step further by compiling the information into a single numerical score. This score can then be used in comparison with similar vehicles of the same age and approximate mileage. The higher a car scores, the better it is compared to its peer group.

Compared to Carfax, there’s a smaller pool of data sources from which AutoCheck pulls from. This means there’s a risk the AutoCheck report won’t be as thorough or complete as a Carfax report. The more limited nature of AutoCheck means there’s no information on maintenance records or emissions and safety inspections, either.

What you do get is title information, open recall status, registration history, accident records, liens or loans against the car, accident history, past flood or storm damage, and lemon status. It also can disclose any records of theft or odometer rollback. All this data is used to compute the AutoCheck score. 

Like Carfax, AutoCheck also offers buyback protection. They’ll buy the car back from you for up to 110% the NADA book value if the AutoCheck report didn’t reveal a prior state-reported titling issue.

Purchasing a Report – Or Finding One for Free

These reports are easy to get: the AutoCheck and Carfax websites are a Google search away, and all you have to do is trade them your credit card information for one of their reports. Carfax is the more expensive at $39.99 for a single report; AutoCheck charges $24.99 for one. Both offer bulk options and lower pricing if you plan on pulling reports for multiple VINs.

That said, you really should only be buying a history report yourself if you’re purchasing from a private seller. Car dealerships very commonly offer history reports for free to prospective buyers; if a dealership doesn’t offer one or balks at the request, that’s reason enough to walk away. Any ethical dealer will want to be upfront with the history of the vehicle, and the cost of the report is, for the dealership, a cheap business expense that’s well worth the peace of mind it will give potential customers. If you end up at a dealer that doesn’t want to get you a history report, shop elsewhere.

These reports can also be found on car search engines such as iSeeCars, AutoTrader, or Edmunds, and sometimes for free. To complement the free Carfax report that’s on most listings, iSeeCars provides everything you should know about a used car including pricing analysis, listings history, and projected depreciation with its free VIN Report tool. 

Alternative Reports

Carfax and AutoCheck pretty much run the show when it comes to vehicle history reports, but other choices exist as well. Here’s a brief rundown on a few lesser-known options:

National Motor Vehicle Title Information System (NMVTIS)

NMVTIS is a vehicle history report put out by the Department of Justice and sold through a few select providers. It discloses title information, title status – junk, branded, salvage, rebuilt, etc. – odometer verification, and loss history. Information is provided by junk yards, insurers, and state DMVs. Authorized providers of the NMVTIS report included carsforsale.com, carrecord.com, titlecheck.us, and vinsmart.com.

An NMVTIS costs $4.95 per report.

National Insurance Crime Bureau (NICB)

Another free service is the VIN check available through the NICB. This report is limited to disclosing whether a car is marked as stolen or salvage.

Things to Keep in Mind

Like anything, there’s always a grain of salt to be taken along with any of the information presented in these reports. These reports are, after all, only as good as the sources they pull from – and these sources might not always have the most up-to-date records. And if anything went unreported, such as a minor accident that wasn’t reported to the insurance company, the Carfax or AutoCheck – or any other report – won’t reflect it.

Rather than use the history report as an end-all be-all, consider it a starting point, a good first hurdle for any car you’re interested in to clear. The report can also be a good corroborator for anything unusual that comes up during a pre-purchase inspection.

As for which report is better, Carfax is generally the more thorough and comprehensive, but AutoCheck will save you money and still provide a complete report. If you want all the data you can get, go Carfax. If you don’t feel like you need to pore through all that information, get the AutoCheck. And if you’re really paranoid, run both reports.

Regardless of which you buy, getting a vehicle history report is an excellent idea before purchasing any used vehicle. It doesn’t matter whether you’re shopping on eBay, Autotrader, Cars.com or iSeeCars.com: a history report can alert you to things you’d never realize – such as flood damage, a branded title, or odometer tampering – and can put you at ease before you pull out your checkbook and sign the papers. 

More from iSeeCars.com:

If you’re ready to start the car buying process, you can search over 4 million new and used cars with iSeeCars’ award-winning car search engine that helps shoppers find the best car deals by providing key insights and valuable resources, like the iSeeCars VIN check report.

This article, Autocheck Vs. Carfax, Which is Best?, originally appeared on iSeeCars.com.