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What Happens When Cars Sit?
We rely heavily on data and logic at Hagerty Insider, but if there’s ever a situation where logic goes out the window, it’s when we see a never-driven, delivery-mile example of a 30- or 40-year-old car sell for beyond top dollar. For example, a Honda S2000 CR with 123 miles sold in 2022 for $205,000, double the Hagerty Price Guide‘s #1 condition (“concours” or “best in the world”) value at the time and the first S2000 to crack $200K. Further down the price ladder but no less surprising, a 445-mile Nissan Sentra SE-R sold for $33,500, or nearly three times the previous record for the model. It’s always a bit shocking when sales like these happen, yet huge prices for ultra-low-mile cars have become a regular occurrence.
The trouble is that automobiles, like everything else, are subject to the law of entropy. “Preservation” is about more than just keeping the odometer reading low. “Like-new” means something different after one, two, or three decades, even if the car still has plastic wrap on the steering wheel. The paint, upholstery, and trim may look flawless—but what about the bits you can’t see, like the complex systems and different materials that make up the driveline? Just because a car is like-new doesn’t mean it actually is new, or that you can just hop in and drive it home. We decided to call up some experts across the industry to answer a big question: What exactly is happening to a car when it sits?
First off, what’s happening to it while it sits depends on where it sits. Imagine a car in a museum—perhaps the Le Mans–winning Ford Mark IV at the Henry Ford Museum in Dearborn, Michigan. Now, think of that old pickup you once saw sitting in a field. Technically, they’re both decaying. One is just decaying far more slowly than the other.
The race car lives in a perfectly curated world. The temperature in the museum is consistent and the humidity is just so: Low enough to deter moisture-loving insects and mold, high enough to prevent the tires and other rubber seals from drying out. A museum car’s tires may barely touch the ground, because the chassis sits on jack stands. The fluids in the car—fuel, coolant, oil—have either been drained or supplemented with stabilizing agents. The upholstery is regularly vacuumed to eliminate pests. Dust barely gathers on the body before someone gently sweeps it off.
The pickup, meanwhile, has been at the mercy of the weather for who knows how long. The tires have cracked and rotted. Salty air might be corroding metal. Insects and/or rodents might be living inside the cabin and engine bay. The engine’s cylinders may be dry, the gas in its rusty fuel tank a kind of goo, the oil gray instead of honey-colored. Its paint may be bubbling, its carpets mildewing.
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Those are two extreme examples, of course, but when it comes to the condition of a car, the storage (or display) environment makes all the difference, whether the car is Henry Ford’s original Quadricycle from 1896 or a brain scientist’s sporty Sentra from 1992. To keep a “like-new” car living up to its descriptor, the temperature must be consistent; otherwise, even the most immaculate car will bake, sweat, and/or freeze. The moisture in the air needs to be high enough to slow the decay of organic materials like tires but low enough to protect from rust. The room itself needs to be well-sealed to deter pests. The vehicle also needs a barrier (or two) between the paint and the dust, dirt, and grime that will accumulate. And that’s only the parts of the car you can see …
The Odometer Doesn’t Tell the Whole Story
No one is more familiar with finding automotive diamonds in rough storage situations than Tom Cotter, known around these parts as The Barn Find Hunter. When we called him to discuss this story, the consequences of bad storage were especially fresh on his mind: He had just bought a barn-find car (a 1986 Porsche 930 Turbo) with 16,000 miles. “That’s the good news,” he said. “The bad news is that it has not been driven since 1996, so nearly 30 years. And even though it had a plastic sheet on it, somehow it got filthy. Filthy. My heart breaks.” Even worse, the windows were open, and the car was infested with mice. It needs a thorough recommissioning: brakes, gas tank, fuel lines, fuel injection unit, fuel injector, fuel pump—and those are just the major areas, says Tom. He’s still in the process of figuring out how much the car needs, but if everything needs to be replaced, the work could cost as much as $40,000. Oh, and he’ll need a new set of tires—the car was parked on its original set from 1986.
“Just because a car has low miles doesn’t mean it was well cared for,” says Cotter. “Cars go bad when they sit.” A perfect storage environment and a sedentary life don’t guarantee stasis, either: “There are things that happen inside the systems of a car that break down, like the rubber in a brake system or the rubber in our fuel system. It doesn’t matter if the car is hot or cold or clean or dirty, those things are going to break down.” One interesting system that is especially prone to degrading when a car sits is the exhaust, he says. “For every gallon of fuel that’s burned in a car, a gallon of water comes out the tailpipe. It’s just part of the combustion process. And so if you run the car and then turn it off and park it for 20 years, you’ve got at least a gallon of water sitting in the exhaust system—most of it, in the muffler. Unless it’s made of stainless steel or something, it’s going to just rot right out. There’s really nothing you can do about that.”
The fluids and the metals in a car are often conspiring against each other. “One of the biggest challenges you have managing large collections—and with cars that sit, too—is coolant system corrosion,” says Scott George, curator of collections at the Revs Institute in Naples, Florida, who knows a thing or two about keeping old cars in peak health. “You’ve got brass, copper, aluminum, iron, steel, all coming in contact with water, and it can create a battery of sorts. It can almost create its own internal energy, which can attack certain metals that are most vulnerable,” like the vanes in a water pump, which are often made of a different metal than the pump itself. Using antifreeze doesn’t eliminate the problem: Those systems can corrode, too, damaging hose connections and water chambers in cylinder heads. “Corrosion in radiators, and things that attack solder and solder seams, are also a big challenge for anybody with large collections.”
Proper storage requires understanding of the car’s construction, because certain materials require special attention and/or precautions. Wool and horsehair, materials that are especially common in the upholstery of cars built before World War II, can attract cloth moths and carpet beetles. Cuong Nguyen, a senior conservator at The Henry Ford, who is heavily involved in the care of the museum’s 300-car collection, suggests vacuuming such cars each season. He also warns that some more modern wiring harnesses are made with soy-based materials that, while eco-friendly, attract mice. Sticky traps, he says, especially those without pheromones, can be good preventive measures for furry pests.
Understanding how a car is built also helps set expectations for how it ages, even in the best conditions. For instance, different sorts of paints wear differently: Lacquer-based paint, used on most cars built before the late 1980s or early ‘90s, doesn’t hold up as well as the more modern, urethane-based version. Another notoriously finicky modern material covers the soft-touch buttons found in some Italian exotics from the 1990s or early 2000s. The black material gets sticky over time.
Best-Case Storage Scenario
Cotter, who owns a storage facility called Auto Barn in North Carolina, encourages enthusiasts to store their vehicles thoughtfully because they’re protecting their financial investment. “It might take you a half-day to get a car ready to lock up, but put a little bit of effort into it. You are maintaining your investment. It’s a mechanical portfolio. A car that’s parked haphazardly will more than likely go down in value.”
The best place to store a car—with any odometer reading—is in a clean, dry place with temperature and humidity control. To avoid flat spots on the tires, which can develop within a year, the car should be elevated, just slightly, on jack stands (as mentioned above, a trick used by museums) or lowered onto a set of tire cradles. If the fuel isn’t drained, it should be ethanol-free; the regular stuff turns into a gummy, gooey mess when it sits. If the fuel in the tank does contain ethanol, it should be supplemented with a fuel stabilizer. If the car was driven regularly before storage, the carpets in the driver’s side footwell should either be completely dry or propped up, away from the floorboards. Cotter explains why: moisture from the driver’s shoes may get onto and under the carpets, and it may mold the carpets or, worse, become trapped between the rubber backing and the sheetmetal underneath, which may begin to rust.
Some sort of rodent protection, even a Bounce sheet, should be taken. (This nifty device, called Mouse Blocker, uses sonic pulses to keep the critters at bay.) One moisture-absorbing trick that Cotter recommends is cheap, and readily found at your local hardware store: charcoal, which absorbs moisture and odors. Ideally, the paint should be waxed and the car put under a cover. Feeling fancy? Look into a Car Capsule, the “bubbles” that the Detroit Historical Society uses to store its cars.
While in Storage
Of course, not all low-mile cars are barn finds like Tom’s Porsche. Many of them present amazingly well. Scott George weighs in. There’s an excitement, he says, about buying a car that appears locked in time and cosmetically perfect—free of nicks, scrapes, bumps, wrinkles. But some people, he says, may not think about what they’re getting into at a mechanical level: “Every time I see a later-model car sell with low mileage, what often goes through my mind is ‘cha-ching, cha-ching, cha-ching.'” He’s seen what can happen when cars sit for 25 or 30 years: “Everything functioning part of the automobile, maybe except for a total engine rebuild, has to be redone.”
Not all buyers may want to drive their pristine, low-mile prize, he admits—some may simply want to be the next owner, to park the car in their climate-controlled showroom as a trophy. There is nothing wrong with that, of course, but down the road, it may be a very costly one—if not for them, for the next person who buys it and wants to drive it. “Cars are operating machines,” George says. “They like to drive.”
At the very least, a car should be started once in a while, and run for more than 5 or 10 minutes—half an hour or so, at least, so that the engine and oil can come up to temperature and cooling fluids can fully circulate. Starting a car and quickly turning it off, says Cotter, “does more damage than if you just leave it alone because the cylinders are dry—there’s not enough oil in the system.”
Acids and moisture can build up, warns George, if a car doesn’t run long enough, “and exhaust systems can corrode from the inside out, and so forth.” He practices what he preaches: The Revs Institute has an unusually high commitment to keeping most of its 120-something collection running, and that means driving the cars—on a 40-, 50-, or 60-mile loop, for the road cars, or on track, for the race cars, whether that’s at a historic racing event or during a test day where Revs rents out a facility.
Where a car is stored may make the most difference in preserving its condition, but how it is maintained during that period is a close second. “I have witnessed actually cars that 25 or 30 years old that literally sat,” says George, “and I’ve seen it firsthand: every functioning part of the automobile, maybe except for a total engine rebuild, has to be redone. The fuel systems, the fuel injectors, all of that stuff.” Maintaining a low-mile car in driving condition requires a balance of commitment and restraint: “There are some people that have just had these wonderful low-mileage cars,” says George, “and they have done annual maintenance and they have cared for the mechanical systems. They’ve just been cautious about how many mile miles they’ve put on.”
In short, the best way to keep a car in driving condition is to, well, drive it.
Before Buying
An odometer reading, then, provides only a sliver of information. The number it displays may be sensationally low, but, for a buyer, the detective work has only begun. The current owner is likely the best source of information on the condition, storage, and maintenance of the car; if the car has traded hands frequently (normal, for some of the lowest mile examples of a particular model), it’s a good idea to hunt down the person who owned it longest. Looking at the car in person, and on a lift, is always preferable, especially if there’s an expert or specialist around to deliver the hard truths.
If you are frustrated in any of those pursuits, and if you still have questions about the roadworthiness of the car, consider your goals. Even if you don’t intend to drive it, a thorough inspection and proper storage are wise. If you crave a well-preserved example of a car you’ve been dying to own, and drive, since your childhood—you and your budget will be better served by a car that is actively driven.
After Buying
Following Cotter’s example and hiring a marque expert to inspect a car is particularly wise, especially if you’re far from an expert in that model yourself. In some very specific cases—an original car with a very special history, perhaps tied to a person—preserving the character of that may be the top priority for a buyer. In such cases, a private conservation firm is an excellent resource.
If a buyer does know a model well and wants to return the car to running and driving condition, the list of necessary checks may be long. The worst thing you can do is rush to start the car before doing a proper diagnosis: If the cylinders are dry or maybe have rusted slightly from condensation, Cotter warns, “you could put probably a decade’s worth of wear on that engine in an hour. Because you’re dragging a dry piston ring on a dry cylinder wall.” Go through every system, methodically, observing everything.
If it sounds like a lot of work to keep a car in top shape over tens of years, it is. Respect for the complexity of the machine is paramount, no matter what the storage or maintenance protocol may be, and no matter the odometer reading or the value of the car. As George says, “The mindset that we’re taking is that we’re in this for the long term, not the short term, and we’re stewards of these cars, and we want to see ’em active in the world for as long as we can.” Respect for the second law of thermodynamics is also critical: We can’t freeze cars in time, and we can only do so much to reverse the effects of time without replacing original parts.
Are low-mile cars worth the hype? That’s a personal call. For buyers and sellers, the more discerning question may be whether they are worth the trouble.
I’m an original owner of a 1973 Triumph tr6. I parked the car in 1980 and hadn’t started it for ten years before resurrecting it in 2004. It was stored indoors the whole time and the interior was still like new. Needless to say, in the last twenty years, I have gone through everything. The vehicle had 38,800 miles on it when stored and since 2004, I have put and additional 42,000 miles on it. I have experienced first hand what the author of this article is talking about. My saving grace is that the car has never seen a Michigan winter where it has lived all of its life, no rust ever and the inter was preserved like new. It’s a better car now than the day I drove it out of the showroom and I currently average around 2000 miles a year.
As an appraiser of classic and collectable cars my advice to clients is, if you can’t drive it regularly, at least once a month then sell it!
I will take every time the vehicle that has experienced regular but gentle use. Fewer headaches than the vehicle that has been sitting for years. Besides, the fun is in the driving, right?
Hi all, I’m now 74 and I have a 1976 MG Midget that I bought brand new and I used almost daily until 1990 when the Lucas “cheat emission inspections” Opus dizzy failed (long story about that Dizzy, think VW scandal). My Dad I had a number of cars that we restored or “refitted,” that is, not basket cases, but ones needing a long list of basic maintenance items to get back on the road.
Dad, born in 1921, and a WW2 Coast Guard and merchant mariner engineer, had a complete recipe for properly mothballing (literally) any type of vehicle, (car, truck, boat, plane) to be stored in a garage or hanger for a year or more. Yes, it included mothballs. And the vehicle smelled like grandma’s old cedar chest until one brings it back out into the world.
I mothballed my MG in 1993 in out detached, unheated 2-car garage/workshop, and properly mothballed it. With 3 boys and schools, the MG had to wait. In 2018, I retired and began surveying the car for refit – not a sign of mice nor insect invasion at all – except in the muffler, where mice built a nest. I had failed to put a sou can over the tailpipe.
If you’d like that recipe, email me: senatore486@gmail.com
I picked up a pristine looking 1986 Firebird that had been sitting with low kilometers since 1994 for $5000. Brought it home and spent the winter getting it running and at a level of restoration comparable to a two year old vehicle. All fluids, most rubber components, fuel system front to back, all brake components, ignition components, suspension components, and tires including the towing and safety inspection totaled about $10,000. All of those costs are with me doing the labor. This for a vehicle with a book value of about $8,000 according to Hagerty doesn’t seem like a good financial endeavor.
The bird has been on the road for the last two summers and has not had a single issue other than a squeaky strut which I replaced again. Bottom line is I would do it again as you just can’t buy these vehicles anymore and I love the body style. Just be aware of what you are getting into before you start.
Actually 1 gallon of water from one gallon of gasoline is not 100% accurate – but “close enough for government work” as the saying goes.
One gallon of gasoline produces about 217.5 moles of water. Each mole of water has a weight of 18 grams. So the burning of one gallon of gasoline produces 3,914.6 grams of water. This is equal to 8.6 pounds of water, which has a volume of 1.033 gallons.
Now only a percentage of that will condense in the muffler but I have seen vehicles run for only short periods of time absolutely REFUSE to run when below freezing due to the exhaust being plugged with ice – and it has been my habit for over 50 years to punch or drill a very small “weep hole” in the bottom of the rear case of any muffler I install to allow the condensation to drain out of the system – even on stainless systems. The weep hole USED to be standard on OEM exhausts back in the sixties and seventies – including on the “ceramic” exhausts on Rambler / AMC vehicles of the time
My 2023 Jeep GC has a weep hole in the muffler. It drips almost constantly especially when driving in city traffic.
Clare, I second your conclusions. I did that calculation a few days ago and got a similar result of just over one gallon. And I would add that even our results are biased low because they ignore the moisture in the combustion air. I did not take the time to quantify how much that additional moisture would add to the total.
I sold cars for over 40 years and fairly regularly when a customer would be crawling under the muffler area they would see the “weep hole” and claim the entire exhaust system needed replacing! A bargaining tactic that was easily explained.
I have a 1966 Corvair Monza that I drive about once or twice a month or more it is nice not to worry about antifreeze.
Corvairs rock!
Hey, I will give you the best advice, I own low mileage real survivor cars, rare judged cars, magazine cars etc. they are in climate controlled storage but I “exercise them”, and I mean at least 25 miles at a time, I try to enjoy the driving experience and although I love looking at them, I really enjoy driving them, anyone of them is ready to fire and go for a ride, they are always in “tuned condition.” Yep they have little fluid leaks, oil, trans fluid, rear end dope etc. because they sit more time than they are driven and they are “old”, but I’m not about to pull an engine or transmission unless there is an actual mechanical reason for it. Cardboard on the epoxy floor works just fine for now.
Finally a well written and more comprehensive article on storage and recovery concerns! Bravo!!!! Here on the East Coast, salt water climates, we include plastic/house vapour barrier under chipboard / ply wood sheathing, often doubled/criss cross pattern on the floor of the storage area. Either always cold, [no garage doors opened on those ‘warm but humid’ days, the kind that immediately create a layer of ‘sweat’ over the entire car/garage], or with a low heat/humidifier on. Also a ceiling fan to move the air and lastly a couple of oscillating fans at floor level moving the air underneath the ‘baby’….. thanks well done!
I just picked up a 1972 Triumph TR6. Hasn’t been driven since 1998. It’s not a real low mileage car, but seemed to have been taken care of. It did fire with a little starter fluid. Now that I’m two weeks into it, everything is bad. Jelly in the clutch master cylinder should have opened my eyes but I wanted one to restore. We’ll, I got it!
Except if you if you want a car as an investment–You need to drive & maintain it it (in good weather) -when buying a driver Condition is more important than Mileage -weather it’s a 10 yr old car of an 80 yr old car–
The mileage thing seems to be unlearnable for most people. I always say it’s about maintenance, not mileage. As a repair tech, I repeatedly see cars with lower miles that have more problems. If it has less than 10k a year, it will need more work. The most reliable vehicles I own have over 200k on them. I even had a customer with a Caravan that needed a ton of work, and he literally said it was worth doing all the work “because of the low miles”. What??!! Where is the actual value?
I bought a 40th Anniversary ‘Vette with just under 50,000 miles on it that had been garaged for 15 years due to the owner’s health. Interestingly, he had the exterior garage doors sealed, heat and a/c installed in the garage, the space carpeted and four recliner chairs arranged alongside the car in front of a big screen tv where he and his friends would gather regularly. In the days before his final hospitalization I heard about the car and his desire to sell it – and I snapped it up based on the storage setup, it’s immaculate appearance and the low mileage. Although I got an excellent price, after I handed over the cash I began to worry about some of the issues in this article. I’m glad I didn’t know about all of them!
After consulting with a knowledgeable mechanic he strongly advised that I have the car pinched onto a flatbed and brought in for an inspection. Long story short, he ended up changing all fluids, hoses and belts and inspecting the brakes and suspension components. I’m not sure what he did about the gas and potentially dry cylinders, but with new windshield wipers and battery that car started and ran perfectly for the next 20,000 miles at which point I sold it for more than I had in it.
After reading this article, I realize how lucky I was.
I change the oil regularly, add fuel preservative, and try to drive them once a year. Easy warm up and low rpm’s seem to work. It scares me that the next time I start one something breaks. $$$!
I’ve just started snow birding this winter, so I now have a modern vehicle at each end of that exercise. The article has made me think more about what I’m doing when I leave one or the other of those vehicles for months on end.
If anyone would like to share their thoughts on what they do with such vehicles, it would be appreciated. (One vehicle is in the Pacific Northwest, and the other in California Desert country.)