Keep your headlights clear with car wax. Just wipe ordinary car wax on your headlights. It contains special water repellents that will prevent that messy mixture from accumulating on your lights; lasts 6 weeks.
Squeak-proof your wipers with rubbing alcohol. Wipe the wipers with a cloth saturated with rubbing alcohol or ammonia. This one trick can make badly streaking & squeaking wipers change to near perfect silence & clarity.
Ice-proof your windows with vinegar. Frost on it's way? Just fill a spray bottle with three parts vinegar to one part water & spritz it on all your windows at night. In the morning, they'll be clear of icy mess. Vinegar contains acetic acid, which raises the melting point of water, preventing water from freezing.
Prevent car doors from freezing shut with cooking spray. Spritz cooking oil on the rubber seals around car doors & rub it in with a paper towel. The cooking spray prevents water from melting into the rubber.
Fog-proof your windshield with shaving cream. Spray some shaving cream on the inside of your windshield & wipe if off with paper towels. Shaving cream has many of the same ingredients found in commercial defoggers.
De-ice your lock in seconds with hand sanitizer. Just put some hand sanitizer gel on the key & the lock & the problems solved.