I don't particularly think the Z4 M is worthwhile as a daily driver over the 3.0si unless your a total petrol head or will be getting your kicks on the track. The running costs are a lot more and unless your going to get your moneys worth out of the performance or youv'e got the money to burn then I wouldn't go for the M.
Really can't see the appeal of the coupe to be honest, I'd choose a convertible over a coupe everyday of the week. Nothing compares to those days when the sun is shining and your driving around with the roof down. I'd go as far to say that I'd have a 2.2i Roadster over a 3.0 coupe for the same price.
I went for the 3.0i in the end and everyone that I've taken out have been shocked at just how quick it was. My cousin has a 325ci and couldn't believe the difference.
Don't forget to try out the 'famous' sound generator when you get one. A bit tiresome on a long run but great fun when you want a bit of fun through some tunnels, plus it's literally a 30 second job
With regards to MPG - Since Ive had it Ive averaged 25.5 MPG. Thats over 2000 miles too. The car see's a dual carriageway/motorway maybe once or twice every couple of weeks (100 mile round trips to manchester). The rest is ALL town driving.
I averaged 39.something on a round trip to manchester (taking it really easy for max MPG just as a test).
Then with cruise *possibly* set to 80-90 all the way, not taking it easy at all, I managed 32 mpg.
Oh and Im 21 so hardly drive around like a grandad.