Quote Originally Posted by GTR27 View Post
I noticed an appreciable difference once over about 10,000k's Gerry. Like 0.5-0.6 L/100 in pretty much all conditions.

Anything over 100 really drops economy, even though the car could easily cruise at 140. On trips where traffic has dictated a 90kph speed, i've seen 4.9 L/100 with me, the wife, 2 kids a boot load of **** and a/c on. Same trip at 110 is about 5.7 L/100
Most of the fuel usage figures for the 1.4tsi I have seen quoted have been remarkably consistent with what we are getting.

However my original posit was that running-in had ONLY made a noticeable improvement at low speed, and it was only remarkable insofar it was the first time I had seen any noticeable long-term improvement on any recent new car (diesel or petrol) I had operated.
This makes sense to me as low speed is where rolling resistance and friction loss improvements would show more readily. At high speed the friction improvements would be less apparent because of the relatively large effects of aerodynamic drag.