Just my opinion, but a bug-out kit should be small enough to allow for ease of transport. Any large kits should be pre-staged at the site to where you are bugging out. That includes all supplies: food, tools, ammo, camping gear, first aid and serious medical gear.

The stuff you carry or throw in your car/truck should be stuff selected to assist in getting to your bug-out location. If you don’t have a bug-out location, you might want to start with that.