[RobUK]

At the price point I was looking at of around £30K before plundering BMW's expensive options list, the 320d and the 328i were within £1K of each other and that was what I was comparing.

However, BMW closed the gap between the 328i and the 330d by making the 8spd Sport Auto box standard spec on the diesel while it's a £1,660 option on the petrol car. The result is that reduces the difference on a strictly like for like basis to just £2,500 between the 328i/330d which I guess is why they are seen as comparable (cost-wise at least).