Convenient and fun, leave your car at one of the Park and Ride lots and hop on a Trolley to the Padres game. There are a few stations near the stadium.
Details: The Trolley station closest to Petco Park: 12th & Imperial. But can also be easily accessed from Park (12th) and Market and the Gaslamp Quarter Station (Fifth Avenue and Harbor Drive). Any of these three stations will serve you.
Cost: A round-trip ticket costs $5 and lasts all day.
Lines: The 12th & Imperial Station, just steps from the Padres ballpark, is serviced by all three lines: Green, Orange and Blue.
View the San Diego Trolley Map.
New: The Green Line now extends to Santee all the way to Petco Park!