I would avoid long motorway journeys like the plague for the first 500 miles of the car’s life. If you’re collecting from a brokered dealership 200 miles from home etc then you might need to take an A-road route for a lot of the way home. I wouldn’t have it driving at constant speed in 6th on a motorway for more than 50 miles in the first 500 and no more than 100 from 501-1000 miles.
My worst VW was a MK5 Golf (140TDI PD) that I bought from Burnley then immediately drove down to Southampton to see relatives (280 miles), hopped onto the ferry to Cherbourg with it and with about 350 miles on, it gave an amber alert for oil – it has drank a litre, taking it below the dipstick. Topped it up, drove around Cherbourg for the day, filled up with cheap booze, took it back to Southampton and onwards home to Newcastle. Another 500 miles on from Calais’ top-up, it needed another litre and drank a litre of oil every 1000 miles after that. Ongoing MPG was sh!te too for the whole time I owned it. Glazed bores I presume from it’s very easy run in.