I always kept a few pieces of winter weather gear in my car, just in case something happened. It was never anything serious, a hat, some gloves, a sweatshirt. However, when I lived in Minnesota I brought along the super cold-weather outdoor gear in the winter. You don’t want to be stuck between Morris and Granite Falls in January, wearing nothing but a suit.
Gear Junkie just did a review on what essentially amount to emergency sleeping bags. Not a bag idea to bring on long day-hikes, or keeping in your car. These aren’t the full size sleeping bags you’re used to, so not like they’re taking up a ton of space. With as many people who get lost in the woods this would be decent. Although, if you’re the type of person to not bring a compass you probably don’t know about these either.