Used Cars | Research and Evaluation | Doing Your Used Car Homework.

Research is just as necessary when shopping for a used car, as it is when selecting a new one—probably more so, though the breadth of useful information is somewhat skimpier when you're buying secondhand.

Used Cars Homework.

Today's shoppers face a bewildering and overwhelming choice of vehicles, whether new or used. Narrowing down the search by planning ahead, focusing on factors that matter most to you, is sure to save time, effort, stress and, yes, money, too.

At least you have access to a lot more information nowadays. Jonathan Banks, executive automotive analyst for NADA Used Car Guide, notes that such independent web sites as AutoTrader.com and Cars.com provide "pricing, content and condition information [that] creates an environment with complete transparency." As we shall see, like those and autoMedia.com as well, many helpful web sites and publications are out there, to make the used car decision-making process even less worrisome.

At the National Remarketing Conference in November 2010, Len Crichter of eCarList advised dealers that, "Your customer is more educated than the dealer, in most cases." That shopper has been researching a single model, or small group of models, and has likely studied several web sites devoted to used cars. More than three-fourths of new- and used-vehicle shoppers research first on the Internet.

Which Vehicle To Buy.

We all have "wants," and we all have "needs." Whether buying a car or any other commodity, decision-making entails a balancing of those two forces.

Unless you're rolling in bucks, or have an emotional attachment to certain vehicles, practical considerations need to be paramount. You can save thousands of dollars by choosing the most sensible vehicle for yourself and your family.

Being realistic, on the other hand, most of us tend to gravitate toward cars that look good, contain features we'd like to have, perform and behave in certain ways on the road—all factors that edge away from the strictly practical.

Ask yourself some critical questions: How old a vehicle would you consider for your used car purchase? Would only a late model used car satisfy? Would you rather pay less and drive home a much older used car? How important is luxury? Will "basic transportation" suffice, or would you be unhappy with a stripped-down model that lacks comforts and pleasures? What about a compromise?

How important is fuel economy? Will a basic subcompact do? Or, must you have a big sedan with a sizable trunk?

Will you be dissatisfied with anything other than, say, an SUV, or a crossover model? How many passengers normally ride along? If you're carrying more than five, you're limited to minivans and three-row SUVs. If you seldom have more than one passenger, a car with a minimal back seat might suffice. If a larger vehicle is in the cards, will it fit easily into your garage or parking space?

Do you crave sportiness, in either style or road behavior? Or both? What about high-performance? How much is enough, and are you willing to pay more for it?

Even though you're buying a used car, how much can you afford? Is your credit good enough to finance a more costly model—and do you really want to? Obviously, the amount you are able to pay (or finance) has to be determined early on.

All these considerations and more should be pondered before you begin shopping. Still, it pays to be flexible, particularly in terms of a particular make, model, and year. If you have your heart set on a specific vehicle, you may be closing the doors to one that might provide nearly all those merits at a markedly lower price. Having one or two alternate choices in the back of your mind pays off, because you have a much larger selection of vehicles from which to make a choice.

Are there specific features that you can't live without, like a manual transmission? That limits the possibilities.

Vehicle Type.

Most likely, you already know which body style and category appeals the most, but here are the possibilities.

• Four-door sedans with a regular trunk come in subcompact, compact, midsize, or full-size models, with front- or rear-wheel drive (or in some cases, all-wheel drive).
• Two-door coupes may have either a minimal or adequate back seat. Coupes aren't nearly as common as in the past, especially in larger sizes. A number of automakers have taken to calling their sporty, stylish models "four-door coupes." They're not. They're shapely sedans.
• Wagons were once the mainstay of suburbia, but they've lost favor in recent years—though a modest comeback may be happening. Most current wagons are midsize or smaller. Early in 2011, Volvo announced that it would stop sending its last remaining wagon to the U.S. market—another sign of sagging wagon interest.
• Hatchbacks and crossovers have captured the hearts of many who might have leaned toward a wagon in the past. Hatchbacks are typically midsize or smaller, though a few bigger examples can be found. Some owners feel almost naked without a conventional trunk, but hatchbacks promise flexible storage capabilities.
• Minivans nearly all have three rows of seats, with seven- or eight-passenger capacity. Five-passenger models aren't common anymore. Most recent minivans have sliding doors on each side, though some with a single slider can be found. Most minivans have front-drive, but a few have all-wheel drive. Four-cylinder minivans used to exist, but recent models are nearly all V-6.
• Full-size vans are mostly sold for commercial use, but some larger families still love them. Vans may have rear-wheel drive, or possibly all-wheel drive. Convertibles have faded in popularity, partly because younger buyers aren't nearly as infatuated with soft-tops as their parents and grandparents were. They're no bigger than midsize anymore and could be front- or rear-drive, usually with a V-6 or V-8, though compacts may be four-cylinder.
• Sport-utility vehicles (SUV) have four conventional doors and a rear hatch (though some have fold-out cargo doors instead). Most are available with either two- or four-wheel (or all-wheel) drive, and could be four-cylinder, V-6, or V-8. Traditional SUVs had a separate body and frame, but most have switched to a unibody configuration in recent years.
• Crossover SUVs, often called simply "crossovers" or "crossover wagons," are the latest trend. They're more car-like in feel and behavior than a regular SUV, though the latter lean more in that direction than in the past. The line between crossover and SUV remains somewhat blurred, but crossovers tend to be a little smaller than full-scale SUVs.
• Pickup trucks may be compact or full-size, with a handful of midsizes around. Compacts usually have either a four-cylinder or V-6 engine. Full-size pickups could have a V-6 or a V-8. Pickups can be strictly basic or lavishly equipped, so the price range is enormous.

Vehicle Age.

Nearly all cars depreciate at a fairly steady rate as they age, though some decline in value far quicker than others. Therefore, the older it gets, the cheaper it becomes on the used-car market. On the other hand, modern-day cars are a lot more reliable and longer lasting than they used to be. So, a car with a few years on it might still have a long and reasonably trouble-free life ahead. Or, it might not.

Cars vs. Trucks.

If utility tops your list of vehicle attributes, an SUV or pickup might be prudent. Gas mileage is nearly always less appealing with trucks, but quite a few of them now boast relatively car-like behavior. Many trucks don't feel very "trucky" anymore. Some can almost be mistaken for luxury cars. Distinctions between SUVs, crossovers, wagons, and even minivans have gotten hazy, so it doesn't pay to set your sights on one particular category.

A while back, used trucks could be found for bargain prices. During the 2008-09 period when gasoline prices spiked, economy cars suddenly began to attract more interest, and their prices rose sharply. At the same time, trucks declined in value. Since then, the normal price gap between compact cars and full-size trucks has been restored, according to Tom Kontos, executive vice-president of customer strategies and analytics for ADESA (a major wholesale auction chain). Full-size SUVs gained about $7,500 and full-size pickups around $4,700, compared to compact cars. "SUVs and pickups have really come back," Kontos said.

Popularity of pickups varies according to region, which means they're likely to be cheaper in some areas than in others. The Plains states have the highest percentage of pickups, according to James Maguire, who studies trends for Experian. In Wyoming, one-third of vehicles are pickups; in Texas, it's 22 percent.

Vehicle Size and Passenger Capacity.

Size, vehicle type, and passenger/cargo space can be the principal deciding factors, overpowering other considerations. The Environmental Protection Agency (EPA) rates a vehicle's capacity according to the number of seatbelts it contains. Be careful here, as some cars—not all of them compacts or smaller—have five official positions, but realistically can carry only four comfortably. In quite a few instances, even two in the back seat are too many.

Furthermore, the line between each of the four vehicle sizes is somewhat hazy. Some cars that are officially compact or smaller are surprisingly roomy, while others may be called mid- or full-size but fall short on spaciousness, especially in the back. Ease of entry/exit is another factor to consider, as some seemingly sizable automobiles aren't as easy to get into as they look.

• Subcompact: what many consider as tiny, but some enjoy for maneuverability and fuel economy (and lower price). Most are four-cylinder with front-drive. Microcars (smaller than subcompact) are common in Europe, but apart from the new Fiat 500, are seldom seen in the U.S.
• Compact: four-cylinder or V-6, with fours gaining in prominence recently. Nearly all are front-wheel drive. Compacts make a nice compromise for singles and couples, as well as small families.
• Midsize: the family favorite, typically V-6; but here too, four-cylinders have become more prevalent in the past few years. Most are front-drive, but some have rear-drive (or all-wheel drive).
• Full-size: once the mainstay, now more the province of luxury makes. You can still find those traditional Ford Crown Victorias and Mercury Grand Marquis with a V-8 and rear-drive, but most family-focused big cars have been front-drive with V-6 (or V-8).
• Cargo volume: What type of cargo do you carry? Grocery bags? Big suitcases? Compare the luggage space's floor area and depth to your requirement. Note, too, how difficult it is to lift a suitcase (which might be heavy) over the bumper and lip to get into the trunk. Hatchbacks can be handy, especially when their back seats fold down to add considerable cargo space. They're more flexible than a notchback model (with a regular trunk). Still, many shoppers won't consider a car without a conventional trunk. Some trunks, even on relatively large cars, aren't as big as one might think.

Drivetrain Layout.

Front-wheel drive became almost the norm starting in the 1980s, until rear-drive began a comeback in the 21st century. Front-drive cars have a more compact, lighter-weight drivetrain and better slippery-road traction, making it more practical in wintry climates. Because more parts are packed under the hood, repairs can be more difficult and more costly.

Rear-wheel drive was used on almost all vehicles until the 1980s, and has achieved renewed popularity lately. Enthusiasts prefer rear-drive for its handling qualities, but winter traction is considerably less appealing than front-drive–even if traction control is installed.

Four-wheel drive can be part-time or full-time. Available on nearly all SUVs and most pickup trucks, 4WD improves traction considerably, especially on slick surfaces. Components are heavier and more complex, and 4WD vehicles are almost always less economical than 2WD–sometimes, a lot less. Most recent systems are full-time, but trucks with part-time systems should not be driven in 4WD when on dry pavement.

All-wheel drive gives the benefits of distributing power to all four wheels when needed, but operates automatically with no action required from the driver. That's because it's permanently engaged. Many AWD car and truck owners might not even realize they have such a system.

Powertrain–Performance Vs. Fuel Economy.

The basic rule used to be simple: a small engine (four-cylinder) was more economical than a bigger one. That's still largely true, but the difference isn't always so great, because V-6s (and even some V-8s) have become more economical to drive. Also, in a heavier vehicle, a bigger engine can actually be more thrifty on gas because it's not struggling as hard.

High-performance models almost always consume plenty of gasoline, though here too, automakers have managed to improve their fuel economy. Many drivers, however, don't operate them in ways that deliver impressive miles-per-gallon.

Plenty of cars, not all of them luxurious or high-performance, require premium-grade gasoline, which costs an extra 20 cents or more at the pump. Some automakers make premium (or mid-grade) fuel an option, recommending it for best performance but noting that the car will run acceptably well on regular, without causing harm.

Consider the type of driving you normally do, and whether you might need the benefits of a bigger engine only rarely, or regularly. On the highway, larger engines can deliver gas mileage that comes close to that of a smaller engine. In the city, that's a lot less likely, and some V-6 and V-8 engines guzzle frightful quantities during urban commutes.

Imports Vs. Domestics.

Because so many import-brand automakers have factories in the U.S. (or Canada), there's no longer a clear-cut difference between import and domestic. Furthermore, parts may come from different countries than the locale where the car is assembled. Japanese makes still excel in perceived quality (and often in actual quality), but American-made models from those automakers differ little from their foreign-built counterparts. American-built cars from the "Detroit 3" also are far better in quality than in the past.

South Korean manufacturers (Hyundai and Kia) have been among the most-improved in recent years. Quite a few cars have been assembled in Mexico, where factories that might once have had questionable quality control have become considerably better.

Traditionally, Japanese and European brands have tended to depreciate more slowly, and therefore cost more. Lately, that gap has shrunk appreciably. Japanese brands have a history of relatively high resale value, as do Europeans. South Korean cars used to be among the fastest-depreciating, but that's been changing. Domestics, too, have improved considerably in retaining their value, though older examples are likely to be cheaper than a comparable import brand.

Base Vs. Step-Up Models.

How important is economy, compared to luxury and sportiness? For obvious reasons, a base model with few extras nearly always costs considerably less than a fully loaded version. Maintenance costs might be lower, too, with fewer gadgets to go bad. On the other hand, base-model cars aren't usually in high demand. So, if you plan to trade it in or sell it later on, a better-equipped model might be wiser. Many shoppers wind up with a compromise: a well-equipped example, but not top-of-the-line.

Condition Is Critical.

No other factor is more important—or harder to assess. Even the experts know they can never be 100-percent certain.

Detailed condition reports, prepared at wholesale auction houses or elsewhere, can now give dealers accurate information about content and condition. Because that information is available, it can be passed along to the retail buyer, too. Detailed and uniform inspections and condition reports benefit everyone. Logically enough, condition is even more crucial for older vehicles.

Mileage is another vital matter, even though modern automobiles can travel a lot more miles without mechanical troubles. Improved vehicle quality over the past decade means even 100,000-mile—plus vehicles may warrant greater consideration.

Average mileage has been going up. Tom Webb, chief economist for Manheim auctions, notes that in 2006, the average compact car sold had 51,000 miles on the odometer. By late 2010, that average had risen to 65,000 miles.

Every vehicle market class has shown higher average mileage. Average mileage on pickups, vans, and SUVs rose by double digits between 2007 and 2010. Compact-car mileage rose 5 percent in that period; luxury cars, 4 percent.

Odometer rollbacks, though illegal for decades, used to be common, especially on cars sold by questionable independent dealers. Rollbacks still happen, but not nearly as much. Vehicle history reports can help you weed out cars whose mileage looks suspicious.

Fuel Economy.

The EPA is the only source of complete comparison data on fuel economy. Their figures are based on simulations rather than real-world driving. For years, critics charged that EPA estimates were overly optimistic, compared to real-world mileage figures; but they've become a lot more accurate in recent years. In addition, the EPA's web site encourages car owners to report their actual fuel-economy figures in ordinary driving, as a comparison.

Three estimated figures in miles-per-gallon are given: one for city driving, a second (nearly always higher) for highway operation, and a combined figure that covers a blend of city/highway use. Estimates vary by engine and transmission within each model. Sometimes other differences have an impact, too. See www.fueleconomy.gov for complete data.

Note, too, whether the car requires premium-grade (or mid-grade) gasoline rather than regular.

Is a hybrid right for you? An electric? Not until the past few years have appreciable numbers of hybrid-powertrain vehicles reached the used-car market. Because of their long battery and powertrain warranties when sold as new, late-model hybrids should have many useful miles left. There's been little evidence that gasoline/electric cars are any more troublesome than those with conventional gasoline (or diesel) engines.

On the other hand, you might want to be more wary of an older hybrid, as those become available on the used-car market. You don't want to have to pay for a whole new battery pack at some point. Otherwise, hybrids can be judged like any other automobile.

Since electric cars in significant numbers didn't reach dealerships until late 2010, few are likely to turn up on used-car lost anytime soon. Best to let the original owners rack up some serious miles and a repair/maintenance history before considering a secondhand battery-powered car.

Safety Features.

Antilock braking has been standard on nearly all models for a number of years, but some non-ABS vehicles are still around on the used-car market. ABS helps prevent the wheels from locking up in a panic stop, especially on slippery pavement. With ABS, you're more likely to be able to steer around an obstacle in your path. We'd steer clear of non-ABS vehicles, especially in snow-belt states.

An airbag "war" has been taking place lately, with even some modestly priced models containing six or more of them. Earlier cars have fewer, and that might be sufficient. All cars must have a frontal-impact airbag for the driver and front passenger. Airbags are designed to inflate almost instantly during a collision. Because earlier airbags were shown to present risks of injury and even death when they deployed, modern airbags are less powerful and designed to operate in stages.

Side-impact and side-curtain airbags came along in the 1990s, and are common among 21st-century vehicles. Side-impact airbags may be mounted in the seat or the door. Side-curtain airbags inflate and drop down from the roof, to protect occupant heads.

So, how many do you need to feel safe? That's a personal decision, but in recent years most airbags have been standard rather than optional, so there may be nothing to decide when shopping for a particular secondhand vehicle.

Recalls and Crash-Test Results.

The National Highway Traffic Safety Administration (NHTSA) recalls hundreds of vehicles each year because of safety defects that have been discovered. Some recalls are initiated by the manufacturer. Not all recalls are of equal seriousness by any means, but when shopping for a used car, it's important to know if:

• The vehicle you're considering has been recalled.
• How serious those recalls were.
• Whether this particular example has had all of its recalls remedied.

See www.safercar.gov to find out if a model you're considering has been recalled, and the reason for that action. A dealer for the make you're considering can check the Vehicle Identification Number (VIN) and tell you if any open recalls still exist.

Every car sold new has to pass a U.S. Government crash test. Eventually, most models also get a second crash test, which results in a star rating (score). Ratings of 1 to 5 stars are given in four categories: frontal-impact (driver's side); frontal-impact (passenger side); side-impact (left) and side-impact (right).

Manufacturers strive for 5-star scores in each category. Because their scores had been improving so much, too many vehicle models were walking with 5/5/5/5-star ratings, impairing the value of the rating system. As a result, NHTSA recently tightened the crash-test procedure, so fewer tested vehicles would get those top ratings.

Look for both vehicle recalls and crash-test ratings at www.safercar.gov. A Search function lets you find recalls by entering the vehicle's year, make, and model.

Off-Lease and Fleet Vehicles Vs. Privately-Owned.

Unless you're financially challenged and must pick the cheapest vehicle around, it's best to steer clear of former rental cars. They're doubtless in better shape and more reliable than in the past, and likely to have been better maintained. Even so, a car driven by dozens—or hundreds—of different people is inevitably a bigger question mark.

Off-lease cars are considered prime candidates, partly because lease agreements require that specific maintenance tasks be done on a regular schedule. For privately-owned cars, maintenance is up to the individual Some folks are meticulous about following the maintenance schedule issued by the manufacturer; others are more lax, which adds to the probability of trouble later on.

Trouble Spots in Specific Models.

Consumerguide.com's used-car reviews include information on specific trouble spots that have plagued certain car models. Consumer Reports surveys its readers' experiences, to derive similar information in a different way. No one can ever predict what will happen to a given vehicle, of course; but awareness of weak spots (if any) can be helpful.

Online forums can suggest possible trouble spots; but remember, some participants may be biased in either direction. Fans of a particular model might report only favorable experiences. Others might enjoy "dissing" a certain model, for reasons of their own rather than based on actual occurrences of trouble. Like all customer reviews and evaluations, reports on trouble spots need to be considered with a grain of suspicion rather than relied upon in full.

Importance of a Vehicle History Report.

Availability of a history report is one of the main reasons why buying a used car isn't as risky as it used to be. These reports, which gather data from a variety of sources, provide details on a given vehicle's title history, reported accidents and damage, and whether it's been a personally-used vehicle (and one-owner). You can also learn when the car was purchased new and where it was owned, and the last reported odometer reading.

Many dealers post Carfax reports for some, if not all, of their vehicles—right on their web sites. Others may want you to pay to see the report, or indicate that you're a serious potential buyer. With so many Carfax-connected online ads out there, you may as well concentrate on those cars that have one ready for viewing. If nothing else, history reports let you weed out the undesirables early on.

Carfax is the best known, but other companies also offer history reports, including AutoCheck.

Questions To Ask About The Used Car.

Asking questions early in the used car sales process not only gives you information about a car that's tempting, but lets you rule out "bad apples" without wasting too much time and effort.

Over the phone, before seeing the car:

• Do you own the car, or are you selling it for someone else (for private seller)?
• Asking price.
• Is it properly titled? Where, and by whom?
• What is the exact model (including year and trim level)?
• Are there any problems with the car?
• Why are you selling it?

Don't expect a totally honest and complete answer to the last two questions, but pay attention to how it's answered–hesitantly, emphatically, warily, etc.

During the Inspection and Test Drive.

• Where did the car come from (for dealer)?
• Can I see a Carfax report (or similar vehicle history report)?
• What do you know about the car's past?

If you see any body damage or other flaws, ask about them. If anything feels odd while driving the car, ask about that—but regardless of the answer, be prepared to walk away if you don't think you'll be happy with it.

Immediately after the sale:

• Does anything else need to be done to conclude the sale?
• Who takes care of license plates, registration, insurance, and financing arrangements?
• Is there anything left to deal with after you've driven the car away?
• Who do you contact with any questions that come up later?

Make sure you have all the relevant documents, and that you know the details of the warranty (if any), including what to do if a problem occurs.

Inspection and Test-Drive.

Never buy a car without a test-drive. No exceptions. Even if you're getting it at a giveaway price, at least a few minutes behind the wheel are invaluable, just to see if you'll be comfortable. Most dealers are willing to allow prospective purchasers to take a drive, either alone or accompanied by the salesperson. Avoid dealers or private sellers who balk at a proper test drive, or give you a hard time.

Don't expect more than 15 or 20 minutes, but try to make those minutes count. Don't let the salesperson distract you from concentrating on how the car feels and behaves–preferably in different conditions, if that's possible to achieve.

Do you need a professional evaluation? If you're paying an appreciable sum, and you're just not sure after your own test drive, it may be worth paying for expert help. Years back, people often had a personal mechanic whom they trusted, who could inspect a potential purchase. Today, with most independent mechanics extinct, it's not as easy to find someone to provide an unbiased inspection. In some areas, third-party inspection services are readily available; but not everywhere. Best to check online, to try and find one in your neighborhood.

Information Resources.

www.consumerguide.com (used-vehicle reviews and valuations), www.kbb.com (used-car valuations), www.consumerreports.com (reliability surveys), www.cars.com (general information), www.usedcars.about.com (general information and trends) www.nadaguides.com (information and valuations from National Automobile Dealers Association), www.autotrader.com (vehicle sources and information), www.carfax.com and www.autocheck.com (vehicle history reports), www.iihs.org (crash tests from Insurance Institute for Highway Safety), www.safercar.gov (government 5-star crash tests and safety recalls), www.fueleconomy.gov (government fuel-economy estimates)

Best Bets (and Worst Bets).

Which specific factors make a car a good (or bad) buy? Any number of publications issue "Best Buy" lists, though not as many for used cars as new ones. Don't expect any of them to have "the answer" for you.

Everybody's different when it comes to car purchase. Don't pay too much attention to anyone's list of Best Bets. What's satisfying to you might annoy the next person, and vice versa.

For instance, most Toyotas have long-standing reputations for dependable and long, trouble-free lives. Even after Toyota's troubles in 2010, over the manner in which recalls were announced, the company's reputation remained largely intact. Some shoppers won't consider anything else, or limit their possibilities to, say, Toyota and Honda—another perennial contender for top reliability as well as thrifty driving. Still, those makes typically cost more, and don't appeal to everyone.

Similarly, quite a few folks won't have anything other than a strictly domestic automobile. Others see all Europeans as superior. Their preferences—and those of evaluators who compile those "best" lists—don't mean a thing unless that vehicle just happens to look good and feel good to you. At the used-car lot, you're Number One, and every other opinion is secondary.

Lists of cars to shun used to be extensive, but not so much anymore, now that car quality has improved across the board. For obvious reasons, those most likely to have been driven hard would be unwise: high-performance or ultra-sporty, and those that appeal most to teenagers and 20-somethings.

What about makes and models that no longer exist? We have more of those nowadays, with the recent disappearance of such makes as Pontiac, Saturn, and Mercury. Ordinarily, cars that were made by General Motors, Ford, or Chrysler can still be serviced at dealerships for a related make. Because these "orphan" makes generally tend to be cheaper than makes that still exist, they can be good values.

Finally, accept the fact that any used car can go bad—either quickly or later on. That's the chance you take when buying secondhand. And it doesn't pay to get distraught if it happens.

Just about every owner of a string of used cars has wound up with a "lemon" once or twice—including the "experts." That's the name of the used-car game, and you just need to move on if it happens to you. Warranties and inspections ease the mind, but nothing is for certain, even though the risk factor has diminished a lot lately.

How To Read The Ads—Online And In Print.

Finally, used-car advertisements aren't what they used to be. Newspapers, for one thing, carry far fewer ads than in the past, now that so much consumer information has moved online. In print, you're likely to find more used-car ads in giveaway "trader" publications than in a daily newspaper.

Online, a host of automotive information services provide access to used cars for sale—whether at dealerships or from private sellers. AutoTrader.com is the leader, but you can easily spend days running through the ads on one site after another.

Not all ads are sufficiently informative, but on the whole they've improved. At the National Remarketing Conference, Kevin Nachbar of the McCarthy Auto Group advised dealers to provide "relevant information. No spin, no hype. Get rid of the car lingo." He further suggested: "Don't waste people's time. They don't have it."

Online ads tend to be packed with photos, but use caution here. Even the best digital photo can conceal a lot of imperfect body surfaces, not to mention trouble spots that are not visible from outside.