I have located a decent place in a forest that i know well, which by midnight will be safe from random wanderers, 200 metres up a disused track. Attach a paper to the screen of the car saying to call the emergency services. The plan is to light the 1kg of coals at the rear of the car so that anyone passing won't remotely notice flames, using wood based impregnated blocks in a chimney and then pour them out into two metal containers and wait for them to become warm but not cool and grey etc. Place them in the back of the car a few feet apart, it's an estate, on bricks, with aluminium foil underneath to dissipate heat.Tape up the door and boot joints with heavy duty tape except for the entry point and make sure the ventilation points are closed in the car. While doing all this i will be drinking a glass or two of vodka and taking a tranquilliser or two, just to try to relax. The ignition will be off, as i have read that co can cause explosions with electrical circuits, i have no idea how true this might be so will use earphones and probably some bach to accompany me.
By then the coals will have been in there for 20 minutes or so and i can check for the heat and how they are feeling. I don't want to wait too long before getting in because otherwise i'm likely to overwhelmed by CO before the drugs really kick in, assuming it's going to plan.Take the powdered down 100mg or so of tranquillisers mixed with vodka if all seems well and lie in the back seats, quickly closing the door.
I can't seem to find a better way with this method after taking notes of everyone's point of view in here.