According to the United States Environmental Protection Agency, transportation accounts for one third of all CO2 emissions in the United States. Automobiles and light trucks generate over half of that, meaning that changing our personal transportation habits can significantly affect our carbon footprint. Here is some information regarding other options to get around:
Bicycling is a great way to get around. It’s fun, great exercise, low-cost, and environmentally friendly. Whether you are looking for recreation or running errands, Santa Clara County has a vast network of bike paths for your use. Check out the Bicycle and Pedestrian Advisory Commission's Bicycle Map of Los Altos  for paths and roads with bike lanes.
Looking to learn more about public transit in the Bay Area? Close to home, the Santa Clara Valley Transportation Authority (VTA)  operates an extensive network of bus and light rail transportation, connecting Los Altos with destinations across Santa Clara Valley and beyond. And within Los Altos, bus routes run the full length of San Antonio Road, El Monte Road, and El Camino Real. Additionally, CalTrain  runs up and down the Peninsula, between San Francisco and Gilroy.
Hybrids, Plug-In Hybrids, Electric, and Alternative Fuel Vehicles
The Bay Area has emerged as one of the top markets in the country for hybrid vehicles. Most manufacturers now offer several hybrid gas/electric models, spanning small compact cars to SUVs. Hybrids offer significantly improved gas mileage, especially in "city" driving, where stops and starts are common.
Plug In Hybrids, known as PHEVs and full Electric Vehicles, known as EVs, offer high mileage ratings. Some Los Altos residents have installed solar panels on their homes so that they can generate additional electricity to help charge their PHEVs or EVs.
Many manufacturers are now introducing clean diesel models, which boast improved mileage ratings versus conventional gasoline-powered models. Some manufacturers are marketing compressed natural gas (CNG) models, which have very low emissions ratings. Ethanol and biodiesel are also on the market, though used primarily as a fuel component in traditional gasoline and diesel-fueled vehicles.
Understanding the relative "fuel economy" of Hybrids, PHeVs, EVs and alternative fuel vehicles can be challenging — especially when both liquid fuels and electricity are involved. The US Department of Energy  is working on this, and offers an excellent resource for information on vehicle fuel economy and side-by-side model comparisons.