I was getting about 25-28mpg out of the mazda subaru between 21 urban and 32 motorway so not much difference, I don't do a massive amount of milage a week so 25-30quids worth of vpower does me. Learning to stay off boost and be sensible helps alot too :-D
Maintenance wise changed arb's shocks and various other bits o the mazda, I've not had the time to work on the subaruuas became a dad last year, but it's pretty much the same you can take it apart with a 10, 12, 14mm spanner and a couple of screwdrivers.
Parts wise only major difference in costs has been a cambelt and accessories change, about 200 for the mazda double for the scoob.