The best way to clean the inside of a windshield (no streaks, no haze)

Step by step: the best way to clean the inside of a windshield

1. 1

   Park in the shade and let the glass cool

   Cleaner flashes off hot glass before you can wipe it, which is what leaves streaks. Park out of direct sun and let the windshield cool to the touch. Morning or evening is easiest.

2. 2

   Vacuum the dash first

   Vacuum or brush dust off the dashboard and defroster vents so it does not land on clean glass. Put a towel over the screen or gauges if you are worried about overspray.

3. 3

   Spray the towel, not the windshield

   Mist glass cleaner onto a folded microfiber towel or the reach tool pad. Spraying the glass sends cleaner onto the dashboard, where it can spot or dull the finish, and puts too much liquid on the glass.

4. 4

   Wipe in overlapping strokes, one direction

   Work on one half of the windshield at a time, sitting in the passenger seat for the right side. Wipe side to side in overlapping strokes, pressing firmly, so the oily film comes off on the towel. Refold the towel to a clean side as it gets dirty.

5. 5

   Buff dry in the other direction

   Right away, buff the same area with a second, dry towel using up-and-down strokes. When you wash the outside, finish with vertical strokes there and horizontal strokes inside; then the direction of any streak tells you which side of the glass it is on.

6. 6

   Reach the bottom corners with a tool

   The base of the windshield, where it meets the dashboard, is where the film is thickest and hands do not reach. Use a windshield reach tool with a clean microfiber pad, or wrap a towel around your hand palm-up and press it into the corner.

7. 7

   Hit stubborn haze with diluted alcohol

   If a greasy film remains, wipe with a towel dampened in a half-and-half mix of isopropyl alcohol and distilled water, then follow with glass cleaner and buff dry. One extra pass usually clears it.

8. 8

   Check from the driver’s seat

   Look through the glass from where you sit, with the sun or a flashlight at an angle. Touch up any streak with the dry towel. Then do the side windows, mirrors and rear window the same way.

Why does the inside of a windshield get a film?

Heat makes vinyl and plastic in the cabin give off oily vapors that settle on the coldest surface, which is the glass. Add smoke, vape residue, breath and fingerprints and you get the haze that causes glare at night.

Carmakers treat this as normal. Nissan’s owner’s manual says it is normal for glass to get a film after the car is parked in the hot sun, and that glass cleaner and a soft cloth will easily remove it. Kia’s manual describes interior glass fogged with an oily, greasy or waxy film, and says to clean it with a glass cleaner following the directions on the container.

Consumer Reports recommends an automotive glass cleaner that contains alcohol and two cloths, one to apply it and one to wipe the glass clean. It says to spray the cloth, not the glass, and warns that a traditional window cleaner may not remove the film inside a windshield and can leave smears.

What not to use on car windows

Skip anything abrasive, sharp or chlorine-based, and be gentle on the rear window. The thin lines on the back glass are the defroster grid, and they scratch or break easily.

• Scrapers, razor blades and abrasive pads: Kia warns not to scrape or scratch the inside of the rear window because it can damage the defroster grid.
• Chlorine-based disinfectants: Nissan says not to use sharp-edged tools, abrasive cleaners or chlorine-based disinfectant cleaners inside, because they could damage electrical conductors such as the rear window defogger.
• Ammonia cleaners on tinted windows: household glass cleaners with ammonia can harm aftermarket window tint. Use an ammonia-free automotive cleaner and check your tint installer’s care instructions.
• Paper towels and newspaper: they leave lint and fall apart. Microfiber traps the film instead of smearing it around.
• Dashboard dressing: shiny vinyl protectants add more oily film to the glass. If you use one, apply it to a cloth, not by spraying, and wipe off the excess.

On the rear window, wipe along the defroster lines (side to side), not across them, and keep pressure light.

How to keep the windshield clear longer

Cut the film at its source and the glass stays clear for weeks instead of days.

• Use a sunshade when you park, which keeps the dash cooler and slows the oily film.
• Do not smoke or vape in the car; both leave a sticky residue that is hard to remove.
• Keep hands off the glass, and wipe the dash with a damp microfiber cloth instead of a greasy protectant.
• Clean the inside glass whenever you do a full interior clean; our guide to cleaning a car interior covers the order of work, and cleaning windows covers the same towel technique for the house.

Mistakes to avoid

• Cleaning the windshield in direct sun, so the cleaner dries into streaks before you can wipe.
• Spraying cleaner straight onto the glass, where it drips onto the dashboard and screen.
• Using one towel for both cleaning and drying, which just spreads the film around.
• Washing microfiber towels with fabric softener, which coats them and causes smears.
• Scraping or scrubbing the rear window and breaking the defroster lines.