Keep in mind that you're probably a lot more likely to successfully flag down a passing car if you're standing next to a disabled vehicle at the time -- and especially so if the vehicle's got some obvious damage.
Additional tips for flagging down vehicles
Highlights include:
Be female
Be a well-endowed female
Have a visible injury
Look them in the eyes
I just thought of a number of female anime characters who sport an eyepatch.
In every single news story that I can remember about someone getting stranded with a broken-down car, the person leaves their car looking for help and they end up dead. Or, if there are multiple people in the car, the one person who goes off looking for help ends up dead and the other people who stayed with the car survive.
My question: If I get stranded in my car somewhere, should I go looking for help? Or should I follow my availability heuristic and stay put? Since I'm still in the process of debiasing myself, should I do the opposite of what this particular mental shortcut suggests, or would that be a sort of bias bias (analogous to the fallacy fallacy)?