You will need to keep moving.
stay in the same place two nights in a row
sleep in front of someones suburban home
park your car for more than 8-10 hours
Find a semi-crowded area where your parked car wont attract any attention (i.e. urban city neighborhoods where people park on the street)
Keep both the exterior and interior of your car clean
I have slept on the passenger side of my car many a drunken nights. Once in SF, I slept in the marina district (semi-nice urban neighborhood). My car was parked in between all the other cars so unless you were to look inside each car, no one would have spotted me. Another time I slept in an adjacent parking lot to my workplace. In both instances, I didnt get the attention of any bystanders or security. Just keep it low key, blend-in, and dont overstay your time in any one place.