Errrrr... as the person who has racked probably the MOST kilometres in a Legnum (as the prior own of Grandpa with 200,000+kms) I can safely say that these cars LOVE long distance trips & there's no detrimental effect on them.
I used my car for a work vehicle for nearly 2 years & as long it was regaularly maintained I had no troubles apart from the usual servicing intervals.
Install a cruise control system & you'll be laughing.
Anyone who says otherwise is full of garbage.