While the DMG includes a table for Airborne and Waterborne Vehicles, there appears to be no such thing for land vehicles — wagons, buggies, chariots, or whatever else. However, there is a table for Object Hit Points, which includes:
Size: Large (cart, 10-ft.-by-10-ft. window) Fragile: 5 (1d10) Resiliant: 27 (5d10)
This is a little less than satisfying from a simulation-model point of view, since a large cart (27hp?) seems like it ought to be a lot more sturdy than many rowboats, which are given on the first table as having 50hp. But, there it is. On the other hand, the rowboat has an AC of 11 (normally for objects made of cloth, paper, or rope), while the Object Armor Class table gives AC 15 for objects made from wood or bone (both perfectly lovely construction materials for a wagon, right?) so maybe that balances out well enough.
It's also important to observe that the object rules include the concept of Damage Threshold — a limit below which any single dose of damage is considered superficial and not counted. On the first chart above, a rowboat has no damage threshold, while a longship is much more sturdy with 300hp and a damage threshold of 15.