Renting a car
If you are going to rent an off-road vehicle or a car, please don't leave anything inside it when you park it: rented cars are easy to recognize by thieves, who won't hesitate to break a window to steal your objects. It's a good idea to leave your car in a guarded parking.
Each time you stop to refuel, you should ask the attendant to check your vehicle oil (aceite, in Spanish) and water (agua, in Spanish) levels.
Please be careful with highway police too: there are many patrols on the main routes, expecially on the interamerican highway. To avoid fines, please respect velocity limits, use safety belts and don't overtake when it's not permitted.
Finally, no parking areas inside towns are easy to recognize by the yellow colour of the nearby sidewalk.