All the tests I've done so far have been in the McLaren 650S, so I don't really have anything to compare it against. I'm planning to also test the McLaren F1 GTR to see if there's any chance it is faster.
GT-ENGINE has a detailed page showing how the Gr.3 BoP has changed in the latest update here: https://gt-engine.com/gt7/cars/gr3/gr3-01-specs.html. There are a lot of numbers there. They might help you get an idea of which cars are better or worse now. Of course, there's no substitute for actually driving them, though.
Testing done for round 1. It's looking like a pretty straightforward race in terms of strategy: just minimize the time on RH tires.
I tested the McLarens -- both the 650S and the F1 GTR. I ran two rounds of tests for each car, taking the better time for each lap for the numbers below. Tests were done in custom races against one opponent, using the fuel and tire multipliers for the race and Afternoon S03 weather, as suggested by GT-ENGINE.
Using the above lap times I'm able to simulate all the possible combinations of strategies from 14RM-1RH to 10RM-5RH. Here they are ordered fastest to slowest:
Manufacturer
Model
Strategy
Total time
McLaren
McLaren F1 GTR - BMW '95
14RM-1RH
22:19.684
McLaren
McLaren F1 GTR - BMW '95
13RM-2RH
22:20.603
McLaren
McLaren F1 GTR - BMW '95
12RM-3RH
22:21.296
McLaren
McLaren F1 GTR - BMW '95
11RM-4RH
22:22.101
McLaren
McLaren F1 GTR - BMW '95
10RM-5RH
22:23.084
McLaren
650S GT3 '15
14RM-1RH
22:27.447
McLaren
650S GT3 '15
13RM-2RH
22:28.159
McLaren
650S GT3 '15
12RM-3RH
22:28.560
McLaren
650S GT3 '15
11RM-4RH
22:29.470
McLaren
650S GT3 '15
10RM-5RH
22:29.974
Note: These simulations don't take into account the order that stints are done in. 14RM-1RH is equivalent to 1RH-14RM.
So it looks like I'll be driving the F1 GTR. I'm surprised that it is so much faster than the newer 650S. Historically, PD nerfed the older cars. Maybe that's changed with the recent BoP. Of course, Deep Forest has always been one of those tracks that favours unusual cars, so it might just be that the F1 GTR is better suited to this track.
Both of the McLarens are MR cars, so I don't know how well the tires RM will hold out on FR cars. If you are driving an FR, I'd recommend running your own test to see how long they last.
I signed for Mclaren yesterday and I was also shocked by how well the F1 GTR performed at Deep Forest. It's not even close between the two cars. This version of the F1 GTR is more similar to what it was in GT Sport.
Also, I agree with you about unusual cars performing well at Deep Forest. I've seen BMW M3s (a car rarely used by players) clocking low 27's in lobby quali sessions. It seems that PD might just have made more cars viable in update 1.72. Which can only be a good thing for GTWS and daily races.
Lastly, in regard to strategy. I was able to complete a race time of 22:30, starting on the Hard tyre for one lap, then switching to the Medium for the rest of the race. The car seemed to perform much better.
