Alright I have something to add here.
I won't be bothered convert my numbers to your odd ways, but the meaning should be clear.

It seems to me Idling and going in 1. gear consumes alot of petrol compared to going in 2.
If I'm driving in heavy traffic and letting the engine idle in 1. but still pulling me gently along i get about 7 KM/L. When I manage 2 put it in 2. the computer shows 10KM/L when idling along.
If I have to stop completely for a while my fuel economy drops dramatically. My average is affected by a few minutes of idling at the traffic lights even if the journey is 15KM long.
/MKay