Michael started to panic a little more as he jumped into the passengers seat. As he opened the door he responded to Evan's claim with a yell "Then they were doing it wrong!". As soon as he got into the passengers seat, he spat the words "Go go go", dropping the pistol on the floor of the car and the butt of the shotgun next to his left foot, the barrel pointing upwards, resting between his left knee and the handbrake.
Michael started stripping his shirt off. "Black blood around the corner on the ground". He yelled. "Stop next to it for a sec if you can, I'll dip my shirt in it".
Michael hoped he didn't have to explain the potential benefits of doing this to the driver. He knew that obviously blood testing would probably be out of the question, unless these demons were just scouts and the world had more time to prepare, BUT at the very least, if the world was about to descend into chaos, maybe he could loot a high school for a microscope and hit the blood with different theoretical "anti-demon" substances to see if there was a reaction. Holy water and silver were two things to test.
Any "cold iron" exposure might also be something, they might be weak against them, so maybe lead bullets coated with iron or steel might be more effective. Also there's palo santo, sage, bronze, salt or maybe a holy symbol?