What are the lines on the rear window for?

Windshield
Source: Pexels
Little Stripes Make a Big Difference
It’s a clever piece of engineering, if you think about it. Up front, we have air vents and wipers. In the rear, a few thin, heated strips quietly replace both, providing clear rear visibility without any moving parts.

So the next frosty morning, before you start fighting with the scraper, reach in and press down on the back window first. Then watch the back window do its thing, transparent streaks spreading across the glass while you continue chipping away at the windshield.