Basic car ownership can be quite a bit cheaper than a horse + carriage.
The horse will probably eat $10-20/day in food. $600/mo in just food costs. Not including vet bills and what not.
A decent and cheap horse will probably cost you $3k up front. Add in several thousand dollars more for the carriage.
A horse requires practically daily maintenance. A carriage will still require some maintenance.
A horse requires a good bit more land, plus the space to store the carriage. Plus, all the extra time and work mounting and unmounting your horse whenever you need to go.
A horse and carriage isn't really cheaper than a cheap car and way less functional.