"If you have someone to share the cost, a rental car can sometimes be well worth the expense as it gives you great flexibility, both in sights to see and in accommodations off the beaten track. I found rental cars in several places running $17 to $20 US per day, unlimited mileage plus petrol. These varied from an old clunker with virtually no tread on the tires and a wonky turn signal (Sri Lanka), to a brand-new car (Maui), but all ran well and were acceptably safe." <Larry Cotter>
If you would like to cross the US cheaply, but quickly, there are 'driveaways', cars that need to be transported across the country. The Auto Driveaway Company 800-562-1558 and 800-346-2277 which has a network of agencies in 75 US and Canadian cities. Look for others in the Yellow Pages under 'auto transport' or 'trucking'.
"Some friends of mine went on an RTW trip and spent six months in Australia. At the beginning of their stay they bought a van, used it for transportation and slept in it most of the time, then sold it at the end of their stay, thereby recovering a good part of their expenses. I realize that there are complications relating to registration and insurance, and that there are risks, but it is an option worth considering." <Wayne Citrin>
"When reselling your car, try to find a bottle of the stuff that strips off the outer layer of wax and "freshens" the look of the paint job. In Australia this is called "Cut & Polish". We used it and sold our car ahead of others that had been in the Traveller's Lot for longer. This lot in Sydney, by the way, is in the Car Park at King's Cross (where all the hostels are). Also, it helps if the car is set-up for travelling. Ours had a mattress and camping stove so the couple who bought it from us were all set to go." <Larry Lustig>
A place in Australia that does buybacks for traveller's is Traveller's Auto Barn.
For those renting or buying a car or van in Europe, I always suggest visiting MotoEuropa Guide and European International Road Signs & Conventions
Also, take a look at Global Car Locator for buying and selling used cars.
A good general link to vehicles is an article in the Traveller's Handbook. For those really ambitious individuals that want to bring their own wheels, and don't mind the cost, delays, shipping hassles, and border bribes, this book has plenty of useful information.
Liliana & Emil Schmid's World Record Tour 1984-onward!
Ursula und Richard Doring auf Weltreise: Around the World in 10 Years
Around The World 1999: Beijing to San Francisco in an old Land Rover Dormobiles