I cruise my TD5 90 up and down the motorways of Britain with considerable enjoyment. The main thing that slows you down is other traffic. In standard trim the TD5 will more than exceed the national speed limit so it doesn't really need remapping. I put an overdrive on mine at the beginning of 2016 which made it a lot quieter for motorway cruising. I can get to Lands End and back in a day from my home in Leicester on 120 bhp. More would be nice but it is not essential. You might be able to accelerate faster with a remap, or hold a higher gear at lower speeds, but it is perfectly happy as standard.