I also think it may fit.
I recently had a suitcase and a massive backpack in my boot (packign for 3 weeks away).. the suitcase was 40cm wide, and on its side.. i had to put the roof shelf up, as the suitcase was flexibl(ish) i had to force it in.. but we were well amazed it all fit, we were going to take my friends Golf to the airport.. but thought i'd give it a try in my car first.
Got no more impracal car jibes from her or my parents since then!
In terms of milage mine is my only car.. but i have access to an estate pool car at work... but i drive 12k miles a year, and get about 350 miles to a tank... so its pretty frugal... better economy then my old S2000 which had a much smaller boot.