Complex sentence: Toyota publicly announced its return to sports car racing in October 2011; three months later the first car undertook a three-day private test session at Circuit Paul Ricard, and planned to run for.
Split into simpler sentences: Toyota publicly announced its return to sports car racing in October 2011. Three months later the first car undertook a three-day, private test session at Circuit Paul Ricard, where it was planned to run for.