Don't believe the (virtual) computer mpg, work it out in reality. The computer is always inaccuratly excessive.
Strangely, I've found Italian cars' trip computer thingy to be pessimistic.
Typically my MJ shows about 55mpg but actually returns 57-59.
A Giulietta 2.0 MJ I hired a couple of years ago showed 52 but actually did 54.
I hired a Golf Bulemotion 1.6D and drove from Mancland to Aberystwith and back overnight fairly briskly. Trip computer - 64mpg; actual on fill up - 54, the same as the Giulietta.
Had a new Focus 1.6 diesel earlier this year and got 56mpg, despite the trip computer telling me I was doing 60 to the gallon.
The problem with my Panda MJ is that I'm over a third of the way to work before it reaches operating temperature, where the fuel consumption should be getting better, but on our frequent 120 mile runs to Middlesbrough the trip computer readout gradually climbs towards 65mpg before it starts to drop back to high 50s as we get closer to the North East, and it doesn't get better on the way back. The best figures I get tend to be on the M6, which, is coincidentally flatter than the M62 and A1(M).
With lower power and torque figures than Puntos or later Panda MJs, maybe that's an answer when climbing some hills on a journey.
I bought the MJ new in 2005 as it was also the most powerful Panda at that time as well as the most economical. I've heard all the Pandas described as having "entertaining handling", yet I find it anything but; perhaps that's down to the extra weight over the nose.
It's also been my own most reliable car, being on its 2nd set of rear shoes, 3rd set of front pads, 2nd pair of discs (my own fault for letting the pads run down to the rivets), original exhaust, original clutch, one front shock, one pair of front anti-roll bar drop links and only 2nd battery. Oh, and one side repeater bulb due to it losing its colour.
I also had the cam chain replaced at about 80,000 miles and have replaced the EGR valve once.
When I bought it in its first week on sale it only cost about £7,000 and I decided I would keep it until one morning I'd come out of the house to find a pile of oxide on the road. I've toyed with the idea of changing it but, it's a bit like trading your old dog in for a new one.....until you look in his eyes, and you just can't.