I tend to agree that loosening up is unlikely to go on for tens of thousands of miles - as I noted earlier in the thread, Mrs b_u's 1.2 appeared to be a bit livelier with over 8.000 miles on the clock than it was with 4,000, especially as it was run at relatively high speeds on the continent for a good deal of the second 4,000 miles - but I don't expect it to loosen up any further. However, after the first few thousand miles I'm not sure that I'd expect to see a significant gain in mpg on the 1.2 - I'm sure the potential's there, and the 100HP seemed to give better mileage for most of the first year - about 10,000 miles - as it showed better flexibility as the running gear ran in as well as the engine - but the 1.2's a different animal, working more nearly to the limit of its performance, and the temptation to take advantage of the slight performance gain seems to be counteracting the theoretical improvement in economy. Mrs b_u's late lamented MJ seemed to ease up over a longer period. Interestingly, the MJ settled down to almost 60 mpg, the 1.2 does just about 50 mpg, and the 100HP gives just under 40 mpg - remembering that we do relatively little stop-start driving in traffic.
