Sleeping in Cars

In my previous entry, Survival Tip for Broke Backpackers, I wrote about sleeping in airports. In relation to that, one of our readers (B.R., an Irish traveler who is planning to take a road trip around the USA) asked about Sleeping in Cars.
Personally, I wouldn't recommend it at all. However, if you are desperate and short of cash…
Off the top of my head, here are a few tips for budget travelers who may find themselves with no other choice but to sleep in their cars:
Women traveling alone should NOT do it at all.
Look for 24/7 truck stops and hospital parking lots. Both locations are more likely to be monitored and are tolerant of people grabbing a few hours of sleep in their cars.
Never park on the side of a deserted road.
Look for campgrounds around the area where you will be driving. Not only will it be a lot safer, you will also have access to toilets.
Go to a gas station and ASK if it's ok to park and sleep there.
Don't sleep with the engine idling. You might not wake up anymore.
I do hope, though, that you save a bit more to be able to afford cheap accommodations (there are quite a few all over) before you start your trip.