Paddock rider Luthi, who has finished in the top five in Moto2 for the past three years, collided with Gresini's Ratthapark Wilairot on Thursday.
Luthi was taken to hospital with a suspected broken right arm and collarbone, while Wilairot was treated at the circuit medical centre for a minor head injury.
Last year's Moto2 runner-up Espargaro was quickest for Pons on the second and third days of the three-day test, setting his benchmark 1m34.577s on the final afternoon.
He was 0.2 seconds faster than 2011 125cc champion Nico Terol, who showed improved form for Aspar to set the pace on Tuesday and remain up front throughout.
Julian Simon completed the top three in combined times for Italtrans, followed by Terol's Aspar team-mate Jordi Torres and the sidelined Luthi.
Reigning Moto3 champion Sandro Cortese was the quickest Moto2 rookie in 21st place, three spots ahead of his former team-mate and fellow graduate Danny Kent.
Aside from Luthi and Wilairot, SAG's Marcel Schrotter was the only other man to have a serious accident, damaging his Kalex sufficiently in a Tuesday crash to end his week.
Vinales dominated all three days of Moto3 testing for his new Laglisse team.
It was a KTM one-two-three, as Monlau's Alex Rins and Ajo's Luis Salom gave chase to Vinales, followed by Aspar's Jonas Folger on the best Kalex and top FTR rider Jack Miller with Caretta RTG.
The leading Moto3 newcomer was Rookies Cup graduate Livio Loi in 14th with Marc VDS.
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