I swear, I thought it was a spec class. The Oreca is all I ever saw.
When the current-spec P2s debuted in 2017 most teams chose to run either the ORECA 07 or the Ligier JS P217 to a lesser extent, mostly since both already had existing relationships with many teams from the previous generation. The 07 also utilized the 05’s tub as the base, which made it easy for teams to upgrade to the new gen, and also provided a known quantity for ORECA to design and develop around.
The Ligier was actually pretty good at downforce tracks but really poor at straight-line speed tracks like Daytona and Le Mans, which was ultimately its downfall - can’t afford to be well off the pace at the biggest events. The gearbox was also pretty unreliable. I think it won once in IMSA at Laguna Seca (overall, when P2s competed against DPi for one season in 2018) and five or six times in ELMS.
The Dallara never had much take up but was pretty quick in a straight line, although it had some porpoising issues too. It won once in the ELMS, at Paul Ricard with the super long Mistral Straight.
The Riley was a disaster, not sure it ever did more than half a dozen races in total in P2 form. This one was also obscenely draggy.
Across IMSA, WEC, ELMS, and AsLMS I think ORECA has 100% exclusivity of P2 entries this year. Although, Sean Creech will move up from IMSA P3 to P2 with a Ligier next year since they already have an existing relationship with the P3 machine there.