Andrea Belicchi was forced to stay in a Le Mans hospital for three days due to sustaining a cracked a rib after an incident sent him head-on into the barriers.
The test day was of paramount importance ahead of the race in two weeks.
The race ended in an Audi one, two, three and a Ferrari double in LM GTE as the Italian cars triumphed in both Pro and Am.
The Swiss team has submitted entry applications for the FIA World Endurance Championship, the 24 Hours of Le Mans and the American Le Mans Series.
Prost had a hugely successful 2012 season with Rebellion Racing.