Was on a straight piece of dual carriageway at night with some friends, we simply used a videotape (mounted on the headrest) which can see the car dash, along with a windscreen mounted origin b2 displaying speed full screen.
We did a few runs and used adobe premier pro to determine the times. Average was 6.5 seconds 0-60. No way to do 1/4 mile times with that.
The 120d is extremely quick for such a small car, I know the 182 is also quick, has good suspension and is very light. I don't believe the 182 can carry much (if any) more speed through corners, but either way, coming out of the corners the 1 series torque will trounce the 182 every time.
We shall have to try it one day, when tuned, BMW diesels provide power throughout the rev-range, I recommend them to anyone. Still, I have to part with her, not because she's old, but because I have had to make a nasty insurance claim recently, bringing my NCD to a mere 0... Insurance doesn't bare thinking about for that car anymore, and I tried a few cars before the Clio, but for cost effectiveness, I like it a lot. But I doubt I'll buy another come a few years.