That is not economical!
33mpg is mediocre at best by any non AMG car standards.
For a non AMG, this is the kind of every day figure at normal speeds. On 'good days' figures hit 40-45+.
It sounds like you were not driving normally (even for a non AMG; let alone an AMG) so what is the big deal? Certainly not every day driving; just as I would not drive around everwhere at 90-100mph!
it was a 40 mile journey, a590 (cumbria) and m6 (cumbria/lancs)...... And i was driving a little 'carefully' and i was overtaken by a caravan.... But....