Rook Carriage gives your gang sturdier carriages so they survive street fights and chases better. It sits between Rook Riders II and Cavalry Call.
Rook Carriage is entry 8 of 17 in the Ringleader branch, one of the three branches (Ringleader, Insider and Swindler) on the Rooks' 39-upgrade board. It is bought with money and materials, not skill points: £5,000, 100 Leather, 100 Silk. Before Rook Carriage unlocks you need Rook Riders II.