never seen it before or have never seen it since. >> the cap was marked with a "v." it was the top to the valvoline motor oil bottle in the trunk. >> the bottle cap was a big indicator right off the bat. the car had been rigged. something wasn't right. >> the bottle cap would be put in there in lieu of a person to hold the gas pedal in position so the vehicle could be operated without a driver. >> to see what effect the bottle cap would have on nick's car, investigators put an identical cap in the carburetor of another car. for safety purposes, a test driver sat behind the wheel to stop the car after the test. when the engine started, the car moved on its own. accident experts estimated the car was traveling at 25 miles per hour when it left the road. the embankment slowed the car. and by the time it hit the water, it was moving at only 15 miles per hour.