You're right, of course, but my point was the A3 was quicker *and* more economical. A colleauge has a manual diesel 1 series, and loves it, and reports it does 45-47 mpg. I'd like to try one to see what I thought, and I'd also like to try petrol/diesel A3s with DSG. Like I said elsewhere in the thread, I think a BMW 1 with a diesel engine, better seats (the standard ones were not supportive) and (maybe) a manual would be much better for me.
The problem with the 120 was I didn't see much past 28 mpg even in gentle driving. I wasn't expecting high 40s, but it would have been nice to see 35mpg or more. We went on holiday from the midlands to the Scottish highlands in it, and the fuel consumption was noticeable- we did a similar journey in the Fabia vRS recently, and despite maintaining a higher avrage speed, didn't have to stop for fuel this side of Glasgow, like we did in the 120. The slushbox, like I said, was far too keen to shift down. I ended up using the manual shift quite a lot.