Marulan to Sydney CBD Fuel Economy

4.0L/100km displayed after 155km at and average of 99km/h. Assuming a 10% error in the computer, that's still 4.4L/100km despite using the cruise control, A/C, the occasional overtaking manoeuvre and absolutely no drafting!

(Anyone familiar with Marulan might know that it is near the end of a plateau that then slopes steeply towards Sydney and falls 600m in about 50km, so the engine is off for much of what is a downhill run. The full Canberra-Sydney round trip is about 4.5l/100km by the computer or about 4.9l/100km by the tank.)