Most of these are pretty good ideas if your car has to be outdoors overnight (or all the time). 

Keeping a bag of cracked corn in your trunk is a good idea that's been around for generations.  My grampa used to carry a gunny sack full of it in his old Ford car (that was back when all cars were black).  The traction from the corn is not only good for icy spots on paved roads, but also good to help with traction if your vehicle is stuck in the snow, as long as it's not a 10 foot snowbank!

https://www.farmersalmanac.com/winter-tips-2-29953