I generally send my characters on journeys without too much drama, and I know what sort of speeds they can make, according to how they choose to travel. I find there are equivalents today which make some sense of travel in the past, and I'll share some lower down.
I'm thinking about this now because I my MIP (Masterpiece/mess/monster in progress) demanded that I find out more about curricles.
My hero and heroine set out in one in an urgent journey and I wanted someone to be able to nobble it at a coaching inn. Of course cutting the reins is an obvious one, but I reckon replacement reins or a substitute would be available. So I went into serious research. I found out a lot, including this illustration. It's from an 1880s book, so the fifty years ago puts it in the Regency.
It shows how very fragile a vehicle a curricle usually was. The lined bit above the wheel is the hood that could be raised against weather. The driver's seat, with space for one other, is thereabouts. The seat at the back is for the groom, sometimes called a tiger.