Improved fuel consumption after 20k?

[spud75]

My 1.9tdi A3 with dpf will regularly see high 3l/100km on a highway run. Worst I ever got was adelaide to Melbourne with a stiff south easter the whole way fully loaded with a bike on the roof with a bike bra on it. (Read sail on the roof) stuck to posted speed limit and got 5l/100km. Sorry but VAG diesels with a dpf van get awesome economy. Same car unloaded started at moint lofty. Qas past norwood before avg consumption was above 2l/100km.

The mk 2 rs will easily do sub 5l/100km on a highway run but I havw seen rhat for a while sinve rhe roof racks and bike carriers stay on all the time. Generally hit 5.0 ok but seeing as always loaded just wont tip under. Need to get all the crap out of the car and off the roof and take for another spin. Still usually doing 800km per 50l tank.

[Gerrycan]

Wow! That is truly exceptional economy from the A3! About 25% better than I would get from the Mk2 in similar conditions.
Although Mt Lofty to Norwood I am surprised you used as much fuel as you did, maybe you had a very strong headwind

Roof racks and the like do not have half the detrimental effect on diesel vehicle consumption as they do on a petrol.
My bikes travel inside, and with minimal dismantling I can comfortably fit 3 people and 3 bikes with luggage.

[daljames]

My O3 Scout 135TDI will average about 5.3l/100kms on my commute from the nthn beaches to Balmain outside of peak times (shift worker). On regular trips to newcastle 4.8 ish (traffic dependent). Towing my caravan (1350kgs) i get around 9.3l/100km towing at 85km/h.

[GTR27]

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

[Gerrycan]

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.