Both San Antonio and Austin are Sunbelt cities organized around the personal automobile. But this doesn't mean that using a rental car is necessarily the best way to explore them. Most of their attractions are located at their cores, which can be explored on foot or by bus. San Antonio's downtown is so attractive and enjoyable it invites walking -- and having a car is, in fact, a liability, not an advantage. And when you need to go slightly farther out, to the Southtown or Monte Vista areas, you can take one of the three trolley bus lines which are color-coded, easy to use, and cost efficient ($1.10). At the visitor center you can pick up a pamphlet with the routes.

Austin's downtown is not quite as attractive as San Antonio's, but it is just as walkable. And if you're not a big walker, any number of buses can get you around downtown and a bit farther south to the SoCo district, or north to the university campus. The city's new light rail line, as it is presently operated, doesn't offer much utility to visitors, but there are plans to build a light rail line between Austin's downtown and the airport. If this project gets approval, it won't be completed until 2015. At present, several buses in Austin Metro's fleet are powered by propane to reduce pollution, and a few more have hybrid power systems. Austin also has an advantage over San Antonio in that it is very bicycle friendly and growing more so each year. There are bike lanes on several downtown streets. From downtown, riders can cross Lady Bird Lake into South Austin very safely. The South First St. Bridge has separate lanes for bikes and pedestrians that are completely removed from car traffic, and next to the South Lamar Bridge is a bridge built solely for runners, walkers, and cyclists. Heading north from downtown, riders can use one of several bike lanes leading into the University of Texas campus. From there, bike lanes lead in all directions, blanketing central Austin.

Austin prides itself on being a green city. In electrical use and generation, Austin leads the country with its conservation programs and investment in wind energy. Austin Energy, the municipal utility company, has won recognition for its work from the utility industry associations and the Department of Energy. The city is generally ranked among America's greenest cities by several organizations, including the Green Guide and Popular Science, who include several energy-usage factors in making their determination.

Though San Antonio isn't at quite the same level of greenness as Austin, it excels in one particular area -- water conservation. This came about more through need than initiative, because San Antonio is dependent for its water on the Edwards Aquifer, a finite resource. To control its water usage, San Antonio has built the largest water recycling and distribution system in the nation. It has also put in place several programs to promote private efforts at water conservation.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.