2006 Legacy 2.0R – Consumption at brakes with engine?

Hello, I recently bought a 2006 Legacy Wagon 2.0R (121kW) with manual transmission. Compared to my previous 1999 Legacy Wagon 2.5 (115kW) I expected the consumption to be a bit smaller, but it is the other way around (although I am trying to drive economically). Granted I usually drive shorter distances, but I did that with the 2.5 as well. Since the new one has a ‘board computer’ I can track the current consumption and at the same time I noticed that the verb smoke is relatively high even though I go completely from gas and so brake with the engine. For example, at 100 km/h from 5th in 3rd gear and only with the engine to 40 km/h ‘braked off’ – however, the indicated instantaneous consumption was always higher than ‘zero’ – at the beginning at higher speed even over 4 l/100km. Is that also so with other 2.0R? Or is that only a mistake with my? Mfg, Danilo