Avengers Mansion Aerial Race
One of the harder races in the game. The first section, through the slopes of K'un Lun, features a lot of (relatively) sharp turns, and the constantly possibility of slamming into the mountain. It's recommended you don't use your double-tap-jump afterburners until you pass into Manhattan Noir, diving under the Brooklyn Bridge.
Even then there are a few tight turns left- it's always better to take the extra two seconds to maneuver correctly than waste time having to double-back for a gate you missed. Get gold and you'll unlock Vision for purchase.
This race ends smack dab in the middle of the Prized Prisoners Puzzle, if you haven't done it yet.