I looked up the Fiesta van...holy crap, thats a van? My sister-in-law had a Fiesta when she was in grad school and it was barely a car. Your version though is cute as the dickens and I see you have the extra-large engine, not the 1.25 litre. My favourite part of the description was that the Fiesta is rated to tow a trailer UP TO 5,500 KG...hmmm, d'ya need a special licence for that? And if you've been towing a loaded horse trailer, muck, that could explain the extra wear on the engine. It's clear what $10/gallon gas can do to vehicle design.   

I'm in Canada not the US but the relative vehicle sizes are the same...what we call mini-vans, you'd find gargantuan. For work I drive a full-size Chev Express van where the back door is in another time zone.

How expensive is diesel compared to regular gas in the UK? It's about 20c/l more here.

Good luck again.
W-O