I agree - Most never believed me that I could get 40mpg out of my 164 3.0 12v. As soon as I moved onto the 164 24v the figures dropped drastically! Thats progress for you - The same basic engine with a 24v head and a move from 192bhp to 210bhp and a drop of around 10mpg at least! The 12v sounded great also and I would not say that performance was noticeably different! Both had the sudden 4k rev rush!
Yes - it's the torque peak that's the problem. It's right up at 5000RPM for the 166 and I expect something similar for the 164 24V. Even though my 166 is higher-geared than the 164, it seems that the 164 is cruising at its 'sweet spot' for economy because it is more or less at the torque peak (not below). I'm pleased that someone else sticks up for my experience, because I was beginning to wonder if there was something wrong with my 164
I used to have an Uno 60 (long ago) and that had no fifth gear. Constant 3500RPM at cruising speed. However it was very economical because the engine seemed to be at its most efficient. The versions with five gears were only more economical at 120km/h - same economy at steady 90km/h.
There must be some sort of balance though, because if you knocked the 166 down a couple of gears so it cruised at 5000, that would probably use even more fuel.
I notice you have the ultimate Ti version of the 166 and that's probably lovely as a nice new car. For me and my old 166 though, I really do feel happier in my 164 - something about the power delivery of the 164 is more satisfying - as you said, the almost-40bhp deficit (230 in my 166?) hardly seems noticeable!
Even things like the window line of the 164 make it a lovely place to be. Back in the 80's, cars were designed with big windows so you get a better view out.
I notice a little more wind noise in the 164 than in the 166. Don't know where exactly but seems to be around the mirrors. So I guess there is some progress in the 166's shape, which most people find a lot more attractive. For me, though, beauty in the 164 is more than skin deep