Hello,
first of all set Event Timeout to like 10-15 seconds. This will be the time, during which you will have to turn vehicle ignition ON, after entering the car, otherwise event will be generated. Because the feature is quite sensitive by default, so right after you open vehicle doors and sit down, device detects that. Other settings should be fine.
As for crash detection, I would recommend to set duration to 10ms and threshold to 2500mG. Default settings are sensitive, and the recommended ones, will help you to eliminate fake events.