I drive mine hard (65hp version) and get 52mpg adveraged after 20k miles. The diesel is a good engine in my opinion the 80hp has a better gearbox (from the 172) though.
No idea what version your after but the suspension needs work if you intend to do any sporty driving as the sports suspension is usless.
It looks beter in black in my opinionas nothing is realy colour coded so in black it looks like it is colour coded if you understand what I mean.
The enemy for economy will depend on how fast you drive at 50~60 where all the torque is in 5th its much better that 80+ on the motorway your looking at 45. I managed 82 on the way to work and back for a week but thats was slow driving. It can drop as low as 36 though if you go complety mad in wales
The 80hp is more economical due to the greater amount of torque but it wont be massive over the 65.
If your looking for a pure economy car what about an Ibiza or Fabia with the PD diesels the sporty models are very quick and economical the Fabia is £10.5k I belive and will hold its value better in my opinion.
EDD