It used to be safer. Your best bet is to stay with a hostel or B&B in town and ask them if you can leave your car there for a few days while you go hike your section. You might have to pay them for shuttles at both ends, but it’s one way to keep your car safe. You can also park in municipal lots and garages if towns have them or in Walmarts and grocery store lots, although it’s best to ask permission to avoid getting towed. Wherever you do park, don’t leave anything valuable in your car, and don’t make it obvious that you’re a hiker by plastering bumper stickers all over it.