In reply to Cheese Monkey:
You probably know this already but anyway... I've just started doing a shorter commute than you in a 10 year old hatchback, and when I go for my next car, economy will come into it but not at the complete expense of comfort. My Fiesta has poor noise insulation, a bumpy ride, and generally just screams at me to slow down when doing motorway speeds. It's not like it can't do them, it just feels like it wasn't meant to for extended periods, and, personally, this can be fatiguing in the early mornings and after a long day. I certainly underestimated who much this would annoy me on a daily basis, but you may not mind.
For this reason I will be going for a 5 door saloon when it comes to upgrade; something like a second hand Volvo, Saab, VW as mentioned above, or if I'm feeling flush an Audi. I get a bit of car jealousy when I see these cruising past without breaking sweat! Plus, plenty of space in the boot for weekend trips.