huh. is this for RotRL? well, it doesn't have to be, I guess.
I thought about putting a two-horse carriage into a run with chase cards, but I couldn't think of a way to accurately model a skill challenge undertaken by two creatures tied together.
Here's what I did recently in RotRL
1. The PCs have parked their horses-and-carriage in the ruins of the servants quarters.
2. One of the PCs goes outside to find the horses surrounded by dozens of evil ravens. At that moment, the horses bolt
(at this point, I ditched the carriage and made the game one of rescuing horses from the carrionstorms)
3. I used the chase cards from packs 1 and 2 to make a somewhat convincing chase where the PCs could either run after the horses or fight/get pecked by carrionstorms (who could move freely). Trouble was I randomized the cards, and a really difficult one was at the top, so the PCs just fought birds mostly. Also carrionstorms suck.
So, you could have a chase where the PCs are trying to rescue something or someone while also engaging in a running fight with an enemy who has superior mobility. How's that?