As gas mileage has become more important, cars have been designed for better aerodynamics. Hoods are lower and more vulnerable to rock chips. Unrepaired rock chips can rust. Touch-up paint repairs look tacky. Repaired or not, rock chips reduce the value of your car. There are three ways to protect it. Read below for a comparison of common car bras, masks and shields.
Ordinary bras are ok when they are new, tight, clean and dry. They have two problems:
Conventional bras are vinyl outside and cloth underneath. The cloth holds water. If you don't remove the bra after rain, the wet cloth will cause your paint to oxidize. The result is permanent clouding and loss of luster on lighter cars and complete color changes on darker ones. In humid climates, not removing the bra will cause mildew, which destroys the bra and the paint. You need to keep the bra dry.
Roads are dirty. Ordinary bras let dirt in and trap it so it builds up. (They also collect leaves, pine needles and whatever else is in the air.) Paint damage occurs from abrasion and chemical reactions with the dirt.
Even new bras move a little at highway speed. This is called flutter. With age they get loose and flutter more. (The "ears" on conventional bras are to reduce flutter and flapping.) Aging is caused by the sun, by stretching, by cleaning and by time. When the bra is dirty, the cloth side acts like sandpaper. Flutter causes it to scratch and eventually wear through the paint.
Bug shields will protect your hood from rock chips. They have three drawbacks:
Many bug shields use spacers to keep the shield off the hood. If the spacers fall off, the shield will rub against the hood and fenders. In a short time it will wear through to bare metal. This can also happen if the shield flexes at high speed - even though it appears to fit when the car is not moving.
Bug shields are fragile. They can break in a car wash.
Driving with an open window reduces gas mileage enough to measure. Bug shields are much worse because they are directly in the airflow. A one mile per gallon decrease in gas mileage costs about $75 per year. You continue to pay for a bug shield after you buy it.
We like clear bras more than conventional bras but they are expensive (over $700 on some cars) and they should be professionally installed. Self-install kits are available but the bra will probably end up with hundreds of bubbles and other problems, similar to window tint film installed by amateurs, and window tint film is easier to install than clear bras because windows are flat. Even professionals take six to eight hours to install clear bras and sometimes ruin them. 3M clear bras are only about 1/4th as thick as the magnetic bra so they don't provide as much protection against larger impacts. Some generic clear bras are only 1/10th as thick as the magnetic bra. Clear bras cannot be removed and re-installed, and over time, a fine line of dirt will form along the trailing edge of the bra, which will be especially visible on light-colored cars.
The magnetic car bra requires far less maintenance than conventional bras, it costs less than bug shields or clear bras and it's the only bra guaranteed not to damage your paint.
Bra removed after a trip through mountains
(click to enlarge)
Flexible magnetic sheet seals cold air in your refrigerator and it seals out water and dirt on your car. The paint under the bra will stay in original condition.
The magnetic bra is designed to exactly fit your car or truck. It will not get loose with age. It will never flutter or flap at any speed. Car washes are no problem. It has no effect on aerodynamics or gas mileage. With the magnetic bra, your car or truck will look great this winter, and it will still look great next spring.