You unlocked the special ability of Roman's taxi.

Complete "On a Pale Horse".

Complete "Cure For Most of What Ails You" and "Get Back in that Hole, Partner" Survivor Missions.

Find and kill a sasquatch.

Complete "Remember My Family".

Kill 500 enemies with any rifle, repeater, or shotgun in any game mode.

Complete "At Home with Dutch".

Complete "An Appointed Time".

Complete a game of Liar's Dice without losing a single die.

Complete 20 story missions without switching to a new horse at a hitching post.

Capture a bounty alive.