I often find slow traffic ahead of me prevents me from accelarating anywhere near best BSFC. There are two usual ways of coping with this: less load and shifting at lower revs. Both of thease sacrifice efficiency.
Lately however, i have been using a third method: coast a bit between gears, this alows more efficient acceleration at the same average rate.
In reality, of course, it's a compromise - you can't be too jerky in dense traffic.

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Remember, even if you win the rat race - you're still a rat.
2010: 454.92L for 5313.90km => 8.56L/100km (27.5MPG US) (5 months)
2011: 606.11L for 7754.04km => 7.82L/100km (30.1MPG US) (Full year)
2012: 170.10L for 2405.00km => 7.07L/100km (33.3MPG US) (In progress)