Despite sharing a border, there is no drivable road connection between Nepal and Bhutan. No official border crossing exists for vehicles (or pedestrians) directly between the two countries.
Travelers must fly (Kathmandu to Paro, ~1.5 hours) or take a lengthy overland detour through India (e.g., Kathmandu → Kakarbhitta → Siliguri → Phuentsholing → Thimphu), which takes 2–3 days by road.