During the active season, most of my gear lives in my car. I can leave at any time and chase locally or short "car camp" over-nighters. If I plan to go further out, I have other gear that rides along, namely clothing/hygiene items.
Aside from personal items like Cell Phone / Wallet / Glasses (+spares), etc...
Full time gear (year round):
Tools
Fluids (for car and for me)
Extra bulbs
First Aid Kit
Cell Booster
400w Inverter
Spare set of clothing / Sweatshirt
Paper Towels
Fix-a-flat
Space Saver Spare Tire
Paper Atlas
For Chase Season I add the following:
Roof rack w/ light bar (LED forward facing ORV Style - BFE wildlife avoidance)
Full Size Spare tire
Nikon D5200 + Nikon D60 with all accompanying lenses/chargers/extra batteries etc.
Chinese GoPro (I think it broke already actually)
Dash Mount (custom)
Tripod
Rain Gear
Portable Ham and GFRS Radios (WX only for time being)
Rain-X
Arkon Seat Bolt Tablet Mount (Customized for two tablets)
Gen 1 iPad
LG gPad 8.3
Small Cooler for food/drinks
Spare Shoes
Bug Spray / Bug Hood / Mesh Jacket
Hat
Sleeping Bag / Air Mattress
There is probably more I'm forgetting, and probably a lot of crap I carry and don't need. Plan to pare down this year so I'm not hauling more crap than I need aka wasting fuel in an already dismal MPG car.
Oh all all this crap is typically kept in plastic bins or bags, and strapped down securely with ratchets. Last thing I want is an emergency situation with this junk loose in the car.