Glass-cleaning products such as Windex should never be used on Tesla’s touchscreen. These products contain harsh chemicals like ammonia that can cause dark spots to appear on touch screens, displays and monitors. However, Windex brand has come out with a cleaning wipe specifically designed for electronics that can be stored easily in your console or glove box and are safe on touchscreens. Otherwise, use a specifically-designed screen cleaning product on a lint-free cloth, or plain water if you’re in a pinch.