6 essential tips for car cover success

Norman Garrett

My driveway has a pecking order. Given that I have only a two-car garage, four cars in my fleet must sit out in the weather. My Porsche 964-generation 911 enjoys the luxury of a garage spot, ensconced there once air-cooled 911 prices went bananas. (The car instantly became a prima donna about the whole thing.) The other spot is for my 80,000-mile, British Racing Green Mazda  Miata: an insurance auction rescue. (She has no idea how valuable she is, nor would she care.)

My son discovered our 914 (subject of another article) languishing outside a race shop. The car was exposed, naked, to the elements for at least 20 years. The car cover on the 914 now is a kind of long-overdue pampering. Our second Miata just got a new top, engine, interior, and we sprayed new basecoat/clearcoat on it six months ago. That car is still glowing from all the attention, but she’ll be living outside for the rest of her life.

My Audi Quattro Avant sits on the street, exposed, in the lowest position on my vehicular food chain. My son’s Miata, the ’52 MG, and the Porsche 914, however, do enjoy partial protection, in the driveway, thanks to car covers. This is mostly a surprise to the MG, known as Abigail, who underwent a fastidious frame-off restoration in a previous life and has not seen weather for decades. Now, like a dog left in the backyard on a rainy day, she sits in my driveway, part of my grand experiment to prove that car covers can work.

man underneath mazda miata driveway maintenance
Norman Garrett


Some background, first. I had the pleasure of having lunch with my friend, super car-guy Tom Cotter, a while back. The subject of car covers came up. He was emphatic that car covers are a collector’s worst enemy. This is the Barn Find Hunter we’re talking about, so he’s seen enough examples over the past decades to lead him to that conclusion. Still, unrepentant hoarders such as myself are often looking for ways to protect our cars when appetite exceeds available storage capacity.

The two main complaints against car covers are as follows:

  1. Trapped moisture between the cover’s underside and the car’s paint can courage corrosion
  2. Paint scuffs as wind shuffles the cover, rubbing against the body.
Car cover precipitation beeding
Norman Garrett

These are valid concerns, which we will discuss one at a time.

Rain, snow, condensation—any type of water wants to get through most fabrics. It is a fact of physics and capillary action. Plastic prevent water intrusion, but tarps are too abrasive and not sufficiently form-fitting. Certain car covers, happily, do resist water intrusion and/or permeation.

The right cover

I went through an experiment with six different brands of covers (big names to “no-names”). This is not an ad or paid endorsement, and maybe you can find a similar-performing fabric, but what is sold on Amazon under the “Motor Trend” brand is working well for me. There are similar cover materials available from other vendors. Naturally, this is a case in which a third party has simply licensed the title’s brand name, but whomever specified the fabric for the covers knew what they were doing. There is a nice, flocked underside to abate scuffing of paint, and the upper surface is waterproof (at least for a time … more on that later).

Proper attachment

So that’s intrusion. Now let’s talk about condensation. Unless you live in ultra-dry conditions such as the desert, moisture in the air wants to condense and collect underneath car covers. I have found, however, that one can ameliorate (but not totally eliminate) this phenomenon by leaving room for air circulation underneath the car. I do this by attaching a sufficiently tight car cover and not letting the sides touch the ground. Straps come with some car covers, and these help, or you can use bungee cords. Routing straps under the car and making them snug will

  1. Reduce wind shuffling the cover (protecting your paint)
  2. Allow air to circulate under the car (reducing condensation)

I also take care to pull the cover up mid-way at the wheels and tuck them behind the front and rear valances to keep open a path for air flow. This way, the cover’s fit is more like mummification than simply draping a napkin over a completed dinner plate. Think of it as a Spanx-like carport—snug, but with room for breathing.

Car cover melting snow line
Norman Garrett

In my experience, at least here in North Carolina over the last three years, this regime discourages the natural moisture rising up from the driveway from condensing on the underside of the car cover. In light rainstorms, the area under the car will stay dry and the condensation “loop” never initiates. If the car is past the point of dampness, then you may want to run a fan under the car on the first clear day to help move out the moisture.

Where to park

I am typically parking these cars on well-draining concrete, which is another big part of car cover success. I have also had good luck parking on pine bark mulch on a well-draining spot that gets full sun. Always park your covered car in the sun, not in the shade. I literally ruined the interior of my son’s Miata by mistakenly parking it under trees, with a car cover, for five years. Lots of animal and mold life (well, first came the mold, then mice to eat the mold, then snakes to eat the mice) took over the cabin. Full sunshine exposure with a car cover will dry out the car after a rain and make the car a bit too hot in the summer for most rodents.

Avoid abrasion: Clean cover, clean car

Your car’s paint should be absolutely clean and well-waxed before you put on an equally clean car cover. Like Old Glory herself, your car cover should never be allowed to touch the ground, lest it could pick up dirt that will be trapped against your car. Also, absolutely no water can be on the car’s surface when you cover it up. Think of your skin under a week old Band-Aid; trapped moisture is the #1 enemy here.

Don’t stand for standing water

Rob Siegel recently had a terrible issue with a car cover trapping moisture on his Lotus Europa and the wetness (and possibly the heat from the welcomed sunshine later) caused big yellow spots to show up on his brown paint. His cover was doing its job on the UV sunshine warfront, but it let water weep through its surface. (Read the complete tale of woe here). I’ve had this problem show up multiple times with my own cars, and it’s because of pooled water. On top of a car cover, pooled water becomes nature’s perfect magnifying glass in full sun, which is how paint like Rob’s can get discolored. Even the best car covers  can absorb water when collected in large amounts like this, creating a steam-cooker between the cover and your paint when the sun shines.

Car cover watermark
Norman Garrett

The best defense here is to use a waterproof cover that also does a good job of shedding standing water. Method of cover attachment helps too; I use carpenter’s clamps to stretch and/or tuck the fabric to make sure the cover is taut and free of areas where puddles might form. Back in the ’80s at Mazda’s Design Studio, we had a theme going where our body shapes were made so that a drop of water would not stay anywhere on any part of the car body’s surface, but would instead flow off to the ground. It made for some lovely shapes (third-generation RX-7 and others), so keep this thinking in mind when you secure your car cover. Yes, it may end up looking like your mother in her robe and hair curlers, but your paint will be safer. And even with all of that, it is still best to be vigilant about clearing any standing water on the surface of the cover after a rain.

Car cover pinching clamps vertical
Norman Garrett

My next pro-tip: Use 3M Scotchguard Fabric Water-Shield treatment. It’s cheap, costing $6 a can from Walmart. When the cover is new and clean, spray it with one full can of this stuff in two light coats, with an emphasis on the sewn seams (these are common leak points). Do this once per month, or when water stops beading on the surface of the cover. There are other waterproofing agents, so select one you like, but I trust the Ph.D. holders at 3M and so far have not had any issues. On those reapplication days, blow and wipe off the cover (while it’s on the car) and get it as clean as possible before spraying on the new coats. Don’t let the spray get on any paintwork, as I am sure that it has some silicone (or other superhydrophobic chemical) in it that would wreck a future paint job. At $6 per month, that is a lot cheaper than a $200-a-month storage unit.

Eyes wide open

Again, if you have an expensive paint job or intact original paint that you are trying to protect, outdoor storage is still a risk. But for “driver”-quality cars, a car cover can work just fine.

Porsche 914 rear three-quarter underneath car cover
Norman Garrett

Final tip: Keep an eye on your engine’s aluminum surfaces (cam cover, carburetor, etc.)—these are the canaries in the mine when it comes to undercar/underhood moisture problems. If they begin to oxidize (white powdery substance on the surface), your moisture content is too high. Move the car to a sunnier spot, or one with better drainage. If nothing keeps the moisture at bay, it may be best to consider alternate storage means.

There! Now you have a way to safely protect your collector cars, and maybe even snap up a few more without fear of them deteriorating. As Tom says, happy hunting.

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    The truth is there is no real substitute for a garage. But many have more cars than garage so covers become the back up.

    Here is what I have learned from selling and using covers for nearly 30 years,

    Most covers can be made of the same material. Much of the market is filled with various Kimberly Clark fabric and while they may name it something different often it is the same for each brand.

    The biggest thing you can do is pick the correct fabric for the conditions you will face. Most covers will leak a bit that is just their nature if they breath. The key is if a little moisture gets in it will come out. So even with the best material do not expect it to be 100% dry all the time.

    Where you are keeping the car matters too as if it is inside or a car port you can adjust the cover to your needs. I use a lighter tight fit cover indoors. It is good for out doors. It does repel water but if it rains hard enough it could get a little moisture bleed. But indoors it really breaths well and it is much easier to store since it is very light weight. It is a top line cover so you get some added advantages with what you pay.

    The fit is key. Make sure to try to get mirror pockets as it will fit the car much better. Also a snug fit will keep air from catching the cover and pulling it off.

    If you have modifications like I do you can work with the company and with some measurements and photos they can make the needed adjustments to make the cover a custom fit. My old cover would not fit the air dam and the rear stuck up a bit due to a rear scoop. They cut it so it fits perfect all the way around.

    If their is an option for a center tie or lock get it. It will prevent theft and or the wind blowing it off.

    I have some cheaper covers that were made of the same top materials but were not cut for the car. For the difference pay it. You will be much happier with the fit.

    Now between companies some cut better than others. The top names mostly have sorted out patterns and you will find they are the best fit. Some cheaper ones may not be as good.

    Above all if you have good paint do not go cheap. Get the best cover and if needed speak to the cover company as they will guide you to the best options to fit your needs. There is no one cover that fits all needs.

    We Midwesterners do not have the luxury or fortitude to park collector cars outside, no matter how well we might cover them. We park them inside, covered, and with a battery trickle charger keeping it on life support.

    Cars covered outside are a haven for mice (I Iive in NC). They love dark and dry places. I learned the hard way with three cars parked outside. I now have a big garage but still cover my cars inside but leave the hoods up so there is a little light exposure and helps cool the engines after driving as they love the heat.

    Anything you cover outside becomes a home for all types of vermin
    My Babe I’ve owned since 69 ,ground up restoration is in a concrete floor garage but not heated 🙁 so I used a Carcoon with 2 small 12 volt fans , basically the car is on stands in a zip lock bag ,no moisture or mice.best investment

    Yesterday I washed off all of the leather dust that was on my 1992 300SL, It gets the dust on it because I park the car in my business building. Today I put the cover on it and sometime next week I will be jacking it up off the floor to not flat spot the tires and disconnect the battery. The building has heat and A/C so yes the car is pampered.

    I have a ’55 Morgan +4 that stays full-time in Haliburton County, Ontario (up north) at our cottage—although none of we humans are there for about half the year. It has always been stored in one of two sheds, under thick cedar-shake roofs, but without any walls. I’m sure that some snow blows in there, but who’d know? Once, in the first shed, a few miles around the lake at my brother’s place, I though it would be prudent to zip and button up the tonneau cover—and yet in the Spring, I discovered a mother coon and her babies had a nice nest, making flaps out of of the upholstery in front of the right seat. I let them alone for a bit, and one-by-one, they all departed for more privacy somewhere in the woods. Years later, I still remember the episode whenever I look down & see the flap—a fault that doesn’t affect the obvious pleasure the car bestows on people wherever it goes throughout the summer. The tonneau doesn’t get closed anymore, but in my own driveshed, I covered the car for winter, and piled Muskoka chairs & whatnot on top. With the windshield folded down, nobody could say that there might be a car under that low pile of junk. Then thinking that winter visitors, let alone car-thieves, wouldn’t stagger through the snow to our place, I stopped putting anything over it. Honestly, when I put the battery back in, in the Spring, it always starts right up, and there is nothing to be seen worse for the wear. And it ‘s too exposed and uncomfortable for the animals.

    The other cars—a ’68 Morgan 4/4 1600-C and a ’76 MGB are parked at home in my stone-walled, concrete-floored open-to-the north “coach-house” Sometimes I cover them (more condensation) and sometimes not (more dust), whatever my whim. When covered, they look secretive—and when not, the cars looks can still be appreciated. If I can see condensation (uncovered option) I can turn on two big house fans, which get rid of it instantly. Either way, I have never seen a hint of deterioration over-winter.

    If you care more about your car than your lawn/yard/parking surface, drive the car onto a tarp to limit rising moisture. A sloped location prevents ponding on the tarp. Then cover as prescribed above.
    RV folks will tell you parking on grass is worse than asphalt which is worse than concrete where moisture is concerned.

    I must add that I have had phenomenal UN-success with car covers. I find that unless a person orders a custom cover (not just one which is ordered in batches from the manufacturer), the cover likely won’t fit.
    I have gone through this problem with more than one company (well-recognized names who sell car covers).
    My wife, who is a good seamstress, redesigned one cover after a large car cover company just could NOT come up with the cover which it advertised for a particular car. Also, this was a “life-time” warranted cover–which usually showed terminal signs of deterioration after only one year. And–they wanted to replace the cover–only if I paid the shipping–which turned out to be a LOT! Cheap covers and expensive covers–I have had poor experience with car cover companies. I also discovered that most (as another reader notes) of the material used usually will be the same–no matter what the description reads. A note of irony here–apparently there is little quality control where the covers are fabricated. One has to wonder if the factory laborers even know what an “xyz” car looks like–much less whether their cover will fit, or not. Can’t they follow the template–which, one hopes, the car company has provided?

    When I do park outside I use two covers. One soft for sun protection and one for rain and moisture if present. I have two cars and 8 motorcycles in a steel garage. Condensation was problem in the winter, so I installed a couple of wind turbines on the roof. Now that is not a great issue. Thank you for the ground protection idea. I will now use water sealant on my concrete driveway.

    That’s me two covers. When I buy a new cover it goes on first then the old one over that. Making it easier to pull off for a quick brush or wash. Inside I keep a tub of moisture eliminator also a small heater fan that I turn on occasionally when tinkering on other car projects.

    I have a 76 Caddy Seville, 1st car all electric, 2 electric fuel pumps, electronic fuel injection, & 1st computer! I got it in 2000, after a Great night at Foxwoods! It had 32k for miles, today it has 39k? I parked it on my flagstone patio for 10 years, all covered up? After 10 years I thought I’d better get it out of Hibernation! The outside was mint, the inside was a mess, rust everywhere under the dash, mold on the leather & headliner, generations of mice in the trunk! Today it is in my garage with the windows down a 1/2″, keeping my 2 Antique Harleys company?? All on Bat. tenders!
    PS, I’m trying to build a 24×24 garage, But, my neighbor has a 80′ Norway Spruce at the base it is 2′ from my lot line, at 18′ it is leaning 6″ into my yard, with branches 24′ into my yard? My towns Building Inspector, Tree Warden, Commissioner of Everything, all NO HELP! Anybody know a Lawyer that would take on a case like this? Thank you in advance, Boston Jim

    I had a car cover on my Porsche 924s. It’s ruined the paintwork. Moisture got under and now the paint has discoloured on the bonnet roof and side panels. Ruined my car.

    I use a Coverking Autobody Armor cover for one of my cars that sits outside. It has nice original paint and is fairly collectible. The miles are high enough that collectors wouldn’t fight over it even though most people think of the mileage as low. It’s a triple layer custom fit cover in excess of $500 and so far so good. It’s in full sun and fits very tight to the car. I polished and ceramic coated the paint and always dust off the paint before covering.

    The cover feels thick (triple layer) but still stretchy and the outside feels like a convertible top. It resists most rain but really heavy rain will absorb into the cover… the car will dry in the sun however. When you strap the cover underneath it doesn’t blow in the wind at all. The cover is stiff and feels girthy which they claim protects from nicks and dings…

    This car came from a garage where it sat for 8 years and had mouse nests in the spare tire compartment and a smell that needed some serious detailing and an ozone generator to fix. Since it’s been parked under a cover for the summers I haven’t noticed rodents. So just because you have a garage doesn’t mean you’re safe from rodents.

    It’s been years and it appears like a garaged car still. I haven’t had mold form in the interior even with the heavy rains and humidity. There’s some mildew spots on the underside of the cover where it rests tight to the glass but so far so good.

    The biggest drawback is the commitment to making sure the car is fully dusted and wiped down before covering. I end up not driving the car as much because you need that 10-12 min to dust it before covering every time to protect the paint.

    The car has a garage space in the winter
    Months at my dad’s garage 90 min away.

    It’s not perfect, but I wouldn’t be able to have the car otherwise with a full garage…

    I find it interesting when you said that various vendors would have similar cover materials available. I wonder if those that can offer custom-fitted truck tarp covers would have specialized materials that the usual vendors do not have. It would be great if they have because it will be a good investment for a truck owner if they can be sure that the design will actually last long and there will be no leaks or issues in the long run. http://edwardscanvas.com/fitted-trailer-tarps-mississippi

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