Homeless - safe to store propane/gas in car while sleeping?

FWIW, gasoline and propane, along with some aerosols, should never be in the passenger cabin of a vehicle. I speak from experience. I was driving a cargo van with 20 gal. propane cylinders onboard. One cylinder that was over-filled discharged through the safety release valve. I could not see my hands on the wheel through the vaporizing propane.