Well, it seems as though I'll have to settle for only having the radio on if the engine's not running while waiting at lights
I've entered fills #2 & #3.
#2 was poor, worse than expected at 6.33 (factory gauge reading 5.8).
#3 was really really good ... too good to be true.
I was expecting about 5.7 (factory gauge showed 5.5), due to finally starting 12 hr shifts and avoiding peak traffic times.
I'm guessing that 5.24 l/100 km is more likely a fill error than genuine economy.