Here is a list of secret outfits found in boss races.
7. Ivan Komrad
I found it, near the end of the race instead of turning left and going up the stairs head right and you’ll see the red marker out on the ice, it unlocks an outfit.
6. Big Cheese
When the cops open fire at the gang. After the first explosion, pass two intersections, its on the left side.
At around 40% of the track (sharp left turn) behind the containers is the red marker. Drive the foward until the right side opens up and drive back on the other side. You will find the red marker at the end.
4. Joe Boomer
At around 59% behind the first firetruck on the left side is the red marker.
3. Sonya Mass
At around 96% you see a white truck on the parking spot on the right side. Behind this truck is the red marker
2. Frau Über
At around 23% behind the gas station is the red marker.
1. Frank Woods
At around 68% you will find the red marker behind ramp you drive down.
Thanks to DΞX STΛRR for his excellent guide, all credit to his effort. if this guide helps you, please support and rate it via Steam Community. enjoy the game.