According to the pilot, he noticed during preflight planning that there was a Notice to Airmen in effect for taxiway construction at the departure airport. He taxied to the runway for takeoff and approached the area of construction, where he observed vehicles parked off the edge of the taxiway. The pilot stated that he was scanning the engine instruments and dialing in a radio frequency when he felt a "jolt." The pilot shut down the airplane and exited, and observed that the airplane's left wing had contacted a vehicle belonging to one of the construction workers. The left wing sustained substantial damage. Other workers at the site stated that their rule was to park their vehicles behind the taxiway lights, in order to leave adequate room for aircraft on the taxiway. The pilot stated that there were no mechanical malfunctions or anomalies with the airplane, and that he was taxiing on the taxiway centerline when the impact occurred.