How to clean the inside of car windows: 5 tricks against smears and fog in winter

In winter the sun sits low, and suddenly you notice it: a grey, smeary film on the inside of the windscreen that dazzles you against the light. On top of that, the glass mists up in the morning faster than the blower can clear it. To clean the inside of car windows properly, you don't need an expensive special kit – just the right technique, so that no streaks are left behind.

These five tricks explain where the film comes from, how to remove it and how to stop the glass fogging up. Similar rules apply to the windows at home – see how to clean windows without streaks.

Why the inside of car windows gets greasy and fogs up

A coating builds up on the inside that you often don't notice for a long time. It has several sources:

• Vapours from plastics: the dashboard and trim release substances, especially when warm, which settle on the glass as a greasy film.
• Breath and skin oils: every touch of a finger leaves a mark, and breath brings moisture onto the glass.
• Smoke: if people smoke in the car, a sticky yellow-brown nicotine film forms.
• Care products: the spray mist from dashboard sprays lands on the glass too.

In winter, condensation is added to the mix: warm, moist air from breathing, wet coats and snow on shoes condenses on the cold glass. Droplets cling particularly well to a dirty film, so a smeary windscreen fogs up faster and clears more slowly.

1. Get the right kit ready

You don't need much for a clear view:

• Two or three clean microfibre cloths, washed without fabric softener. Our guide on how to wash microfibre cloths explains how to look after them.
• A shop-bought glass cleaner – for windows tinted with aftermarket film, an ammonia-free one.
• Or a home remedy: lukewarm water with a splash of methylated spirits or a little vinegar. Vinegar and alcohol are among the simple household remedies that the Swiss consumer protection foundation (Stiftung für Konsumentenschutz) recommends instead of lots of special products.
• A windscreen cleaning wand with a swivelling head for the hard-to-reach lower corner of the windscreen.

2. Interior first, then the glass

Otherwise dust and spray mist end up on the freshly cleaned glass. Vacuum the dashboard, air vents and seats first, then wipe the surfaces with a damp cloth. If you use a dashboard spray, apply it beforehand – sparingly, and onto the cloth rather than straight onto the plastic.

A garage or a shady spot is ideal. In bright sunshine the cleaner dries too fast and leaves streaks; below freezing, water freezes on the cold glass.

3. Clean the inside of car windows in two passes

1. Spray the cleaner onto the first cloth, not onto the glass, so nothing drips onto the dashboard, speakers or electronics.
2. Wipe the glass in overlapping lanes, with light pressure and several passes if the film is thick. Turn the cloth often.
3. Buff immediately with the second, dry cloth before the cleaner dries.
4. The corner between windscreen and dashboard is easiest to reach from the passenger seat, using the back of your hand or the cleaning wand.
5. Finally, check the glass at an angle against the light and buff away any remaining streaks.

A nicotine film often needs two or three passes, each with a fresh cloth, until the glass no longer has a yellowish sheen.

4. Rear window, side windows and sensors

• Heated rear window: wipe along the heating lines, not across them. No blades and no abrasive cleaners – the thin conductive strips can be damaged.
• Tint film: only ammonia-free cleaners, soft cloths and no blades; follow the film manufacturer's instructions.
• Side windows: lower the window a little so you can also reach the top edge, which otherwise disappears into the seal.
• Camera and sensors behind the rear-view mirror: wipe carefully around the housing and don't take anything apart.
• Displays: only as the car manufacturer recommends, usually with a dry microfibre cloth.

5. Prevent fogging in winter

• Fresh air instead of recirculation: in recirculation mode, the moist air stays in the car.
• Use the air conditioning: it dries the air. If your car allows it, let it run in winter too and direct the blower at the windscreen.
• Get wet things out: knock snow off your shoes, don't leave wet coats and floor mats in the car, and empty rubber mats.
• Cabin filter: a clogged filter lets less air through. Have it checked and replaced at the garage according to the service schedule.
• No frantic wiping with a glove or sleeve: it smears grease over the misted glass and makes the view even worse.

Common mistakes

• Wiping fog away with a glove: it spreads grease and dirt, and the glare against the light gets worse.
• Too much cleaner: leftovers dry into streaks and drip onto the dashboard.
• Fabric softener in microfibre cloths: the fibres clog and leave smears.
• Blades or abrasives on the rear window: the heating lines can be damaged.
• Switching on the wipers on an icy windscreen: the blades can tear – remove the ice first.

Priority Clean editorial teamOur cleaning team from Alberswil, Canton of Lucerne, shares hands-on experience from move-out, house, office and window cleaning across Central and Northwestern Switzerland.