On May 11, 2007, about 0900 Pacific daylight time, a Piper PA-38-112, N2539D, taxied into a service vehicle that was parked on the apron south of runway 26 at the Mariposa-Yosemite (uncontrolled) Airport, Mariposa, California. The ground collision occurred while the pilot was taxiing for takeoff. The airplane was operated by Mazzei Flying Service, Fresno, California, and it was substantially damaged. The commercial certificated pilot was not injured during the personal flight. Visual meteorological conditions prevailed at the time, and no flight plan had been filed. The flight was performed under the provisions of 14 CFR Part 91, and it originated from Fresno about 0730. The pilot reported to the National Transportation Safety Board investigator that his flight from Fresno to Mariposa was uneventful. The pilot made several touch-and-go takeoffs and landings after arriving at Mariposa, and then he made a full stop landing. Thereafter, he opted to taxi back for another takeoff on runway 26. While proceeding in an easterly direction on the centerline of the taxiway that parallels runway 26, he observed a stopped vehicle on the apron, to the left of his airplane. The pilot indicated that he continued taxiing on the taxiway, but his left wing tip impacted the vehicle. The vehicle was located to the north (left) of the airplane, and it was parked partially on the apron and partially on the taxiway. No other airplanes or vehicles were in the area of the taxiway or apron at the time of the collision. The area to the south (right) of the taxiing airplane was available for use by the taxiing airplane. The pilot indicated that he could have either stopped or altered his course off the centerline of the taxiway to avoid the parked vehicle. No mechanical malfunctions were reported with the rented airplane. The impact dented the airplane's left wing and bent its fuselage.