Robert Downey Jr. and Zach GalifianakisAh, the road trip; a cinematic rite of passage that takes best friends, estranged family or mortal enemies on unlikely journeys in search of love, enlightenment or the perfect buzz.

Todd Phillips' 'Due Date,' opening this Friday, is the latest in a long line of great American road trip movies, a manic mash-up of 'Planes, Trains and Automobiles' and 'The Hangover,' with Robert Downey Jr. and Zach Galifianakis as two unlikely traveling companions forced together by bad luck and Galifianakis' own ineptitude. Downey is a father-to-be, trying to rush back home in time for the birth of his child, while Galifianakis and his too-friendly dog, Sonny, are on their way to scatter his dead father's ashes at the Grand Canyon -- as you can imagine, mayhem ensues.

In honor of 'Due Date,' we've composed a list of the top 7 tips that any aspiring road-tripper needs to remember in order to have the best (or worst?) journey ever. So stock up on your drugs, get your motor running, and hit the road with us.
Midnight Run
Based on 16 critics

Scruffy bounty hunter (Robert De Niro) brings in fussy embezzler (Charles Grodin). Read More

Due Date
Based on 39 critics

A high-strung man (Robert Downey Jr.) takes a road trip with an annoying stranger. Read More