Has anyone worked out how to get the Leader of the Pack, Pony Up and Atomic achievements yet? The description for all three of them say "Win a race in [appropriate car] in freeplay with maximum opponent cars." I've won a race with the 2017 Ford GT in freeplay with 24 opponent cars with the drivatar set to Unbeatable and I still haven't unlocked the achievement.
I would say it's a bug, but apparently there are a few who have beat it. Still, could be a bug.