All I can say is you must love the left hand lane
The 1.2 is probably the most depressing thing I've ever driven on a motorway, it's lovely on A and B roads but you are kidding yourself if you think you can comfortably keep up with the traffic on a motorway in it without having to change down when you come to a hill.
I'm not slimmer of the year, but has no problem even 2 up keeping up with traffic in 5th, don't forget its not supposed to be no Abarth or AMG!
Happily sits at 85mph on private road I once used, a different one to Maxi I suspect, with a fair few hilly sections
I looks like you seem very set in your opinion, perhaps we'll have to agree to disagree and OP can make up their own mind on a test drive.
If the 1.2 is as incapable as you make it out to be then I question why it has sold so well and is still used by Fiat