Intel from top split Nations regarding car choice (though more like 1.5 split due to lack of top drivers in bottom half):
911 GT3 - fastest over one lap, but race pace declines due to tyre wear (down to half by the end). A little fuel saving required (some people ran out near the end). Good brakes and acceleration, but understeers in high speed corners due to 0/200 downforce.
XBOW - slightly slower than 911 GT3 over one lap, but better race pace IF you can handle the twitchiness. No issues with tyre/fuel at all. A bit worse brakes/acceleration but high speed corners are its forte due to 200/300 downforce. Also I find the gearing a bit awkward for the downhill chicane so it can be inconsistent thru there.
F40 (my choice) - the dark horse (pun intended). Slightly slower one lap pace compared to two above, BUT combines the XBOW's tyre life and the 911 GT3's handling safety (relatively speaking, there are easier cars but they're much slower). Neutral handling in slow corners and only a hint of understeer in high speed stuff. The gearing is also quite long so you can save time shifting less by just leaving it in higher gears (also acts as in built TC from the slow corners). I qualified 15th-ish and climbed up to 9th, thanks to people in XBOWs going sbinalla, 911s running out of fuel and the usual demo derby casualties
SFR - the safest choice handling wise, but the slowest in terms of speed. Useless when it falls out of draft and if you mess up the downhill chicane, you lose so much momentum going up the hill you will fall like a rock. Probably a good choice in lower split rooms, just play it safe and wait for others to mess up.
Other choices I tested - F50, Ford GT 2017, Citroen GT - they're all very safe to drive, but the laptime is just too slow. Having said that, Nik Makozi handicapped himself using the Citroen and still finished 2nd. It was a hard fought race though, and I have no doubt if he used the 911/XBOW he would've finished miles ahead.
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Manu is an interesting one. We don't race often at St Croix and it shows because I qualified higher than usual
All I can say is slipstream is critical, but don't start the lap too close or you run the risk of running into each other because of the long lap. The key here is knowing which corners to take early apex, and which to late apex. It can be tricky because looking at the map they all look like identical 90 degree turns, but each have their own personality. It's a bit hard to pick up from watching replays as well, you just gotta drive enough laps to "feel" which is which.
Strategy wise, on paper 1 stop (7M+1H) is faster. HOWEVER, if you're on Hards and you manage to stick to slipstream and avoid battles while the Medium runners all trip over each other, you can juuuuust pipe them on the final lap as they come out of the pits. In my race an NSX started 3rd, no stopped, fell back to 8/9th in the race and passed our group (which had been battling all race long) just as we came out of the pits to take 3rd again. It's really tight though. You just gotta make sure you're within the 8 seconds pit stop time loss.
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Another thing after the update, the reduced collision "pinball effects" definitely makes it a bit easier to run door-to-door. In a way it's good because small touches here and there don't mean instant death, but on the other hand people will see this as invitation to be more aggressive. The line between hard racing and straight up punting becomes a bit blurred. It's okay if you're racing against clean people, but IMO it doesn't really change anything if someone is dirty because the penalty system is still too lenient most of the time.
disco'd...
Finally made it to DR A too! 
I was just being outclassed on the straights.
