Wow.That must have been some road trip back then. Cars needed so much more maintenance in those days too.
Did they? You had to do more adjusting, like point gaps, tappets and the occasional carb tune, but none of it took very long. I reckon I could do all of that, plus change the oil and both filters on my Avenger in about 45 minutes. That's less than £50 of parts; the Mitsubishi GDi I used to have would have cost more than that just for the 4 plugs.
Now look at what you have to remove on a modern car to change the oil or plugs, or the oil, air and fuel filters. And that's not counting things like cambelt changes. Considering I used to be able to do a Pinto belt in under half an hour(at the side of the road once!), I'm not convinced that moderns are any better. They are certainly not as easy to work on.
A couple of years ago a friend used a Triumph Vitesse as his daily, and was doing about 30,000 miles a year. It let down once, when the water pump failed on his way to a job. He rang the breakdown service, and had it recovered 15 miles back to his boss' house. He said he removed the pump whilst Clive cycled down to Quillers with £25 for a new pump. They fitted it, and drank their tea while leaving it ticking over to check for leaks, and then setting off again for Dunsfold. Total time off the road was 90 minutes! Try that on the car's modern equivalent, a 330 BMW.