Done a few lengthy road trips in States late 1990s. One was Houston, Texas to Grand Canyon, Arizona and back. With a few detours was best part of 3,000 miles. Quite a lot in just under 3 weeks, but in a big Buick with V8, aircon, cruise control and their excellent roads it didn't feel as gruelling as it would doing that kind of mileage in UK. Other trip was NYC to Tennessee, but more sensibly this was only one way.
Done a fair few miles in South Africa, from Johannesbury/Pretoria, down to Durban/Pietermaritzburg - then down to Cape town taking in the Garden and Wine Route.
Drove to Czech Republic for all of Nov and Dec 2021, staying in small town on far side of the country near Ostrava. Was on my own and did the 1100 miles leaving Bristol on Monday morning, arriving CZ Weds lunchtime. Was knackered - slept most of a day on arrival. Return trip was a lot more leisurely and spent 4 nights in rural France (Calais area, near Watten) before getting ferry to Blighty.
One thing about hiring cars, particularly the ones we hired in South Africa, is they include several hundred kilometres in the price, but charge extra for every Km over that limit. You soon learn where the speedo cable unscrews from the gearbox. Just have to remember to reconnect it before handing car back.