Complex sentence: His promising career ended abruptly after a crash in the 1964 Indianapolis 500 in which he was killed along with fellow driver Eddie Sachs in a fiery inferno that directly led to a change in fuel type from gasoline to methanol.
Split into simpler sentences: His promising career ended abruptly after a crash in the 1964 Indianapolis 500 in which he and fellow driver Eddie Sachs were killed. The fiery crash directly led to a change in fuel type from gasoline to methanol.