Drove it to Pickering for a short break. These diesel’s are in their element just cruising along motorways. A journey of 230 miles and it cost me peanuts in fuel. 
As soon as mine gets beyond around 70mph, it has a drink problem worthy of any AA attendee, and virtually always returns 32mpg (reality, not the trip computer) over an entire tank. Last tank was 35.9mpg - she'd used it for work and to nip to Oxford, and clearly she is more reformed than me...
I've had 67mpg from her little diesel going to work over a 70 mile run to central Brumingham, but I was keeping it under the instant ban territory...
I set the car alert to 70mph.
It gets angry and keeps flashing a dash warning and makes a bong noise if I go over the set limit. I told you, I'm fully converted now. 
Mine's set a bit higher than that

(NB. For use on my private test track officer

)
I do regularly use the speed limiter for roadworks etc, mine only has standard cruise, not the radar active version found on later cars so is more of a pain to use on busy roads, hence preferring the limiter.