Go Ahead, Pour Warm Water On Your Frozen Windshield. See What Happens

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Rapid change in temperature is just plain bad for glass. Particularly for a large sheet of glass — like a car windshield — pouring warm water on frosty glass is likely to crack or shatter it, as the warm parts expand at different rates from the cold parts. The glass will crack simply to get away from itself. It’s a very simple scientific experiment; just wait until a below-freezing day and walk out to your car with a hot kettle of water. Boom, within seconds, you’ll have a broken windshield. If you’re not willing to risk it, you can always use a little plastic scraper to get the frost off. Or move somewhere that doesn’t frost. Or get a place with a heated garage.

Prompted by video of an early morning carjacking in the UK, retired London police officer Norman Brennan took to Twitter to advocate against starting your car to warm it up in your driveway. Or in his extremely British words, “do not leave your car ticking over on your drive.” Brennan then writes “a bottle of warm water clears your windscreen safely in seconds (been doing it for 40yrs).” Which we’re just going to have to say you should never do.

The video linked in his tweet depicts the car owner coming out to see his car in the process of being stolen. Instead of going inside to call the police, he wrenches the door open and confronts the thief head on. He’s then dragged backward down his driveway by the open door and slammed headlong through a brick wall. If, as a police officer, you are going to advocate for something, maybe it should be taking a step back and letting the criminal leave without harming you and sorting it out with the police and insurance company.

Look, car theft is a fact of life in the U.S. right now, as nearly a million cars were stolen last year. That’s less than one third of one percent of all the cars that exist in the U.S. right now, so maybe even as car theft becomes more common, it’s still not as common as you might think. In the case of the carjacking in this video, it was a crime of opportunity, and could have been thwarted in many ways. A simple suggestion, if you’re going to leave the car running in your driveway, at least lock the doors. And if the criminal starts to drive away, don’t get between your now-stolen car and a brick wall. You’re going to lose.