I have tested this and found that with a light car hard accellerationup to speed and then cuising on a light throttle was more economic then slow acceleration through the gears.
It works on the basis that 20mpg for 10 seconds uses less fuel then 35mpg for 60 seconds before cruising. On this basis I will drop a couple of gears and blast up a hill quickly rather then slog it out in top gear for a minute or so.
+1
How to drive a standard cinquecento/seicento economically on open roads:
1) accelerate briskly (circa 70% throttle) to a speed where the engine is just on-cam in top gear - about 60mph on MPIs & SPI sportings, about 55 on MPI sportings
2) If you encounter a hill that makes you increase the throttle noticeable then change down until you're easing off the throttle
2a) if in a SPI 'cento sporting & it's over about 7% gradient nail engine to the red line (note: the 6000rpm red line is a function of std cam profile & ignition timing not cooling capacity or engine revving ability, standard limiter was at 7200rpm but often were good for more like 8000rpm).
This will see you make a mockery of all official fiat fuel economy figures assuming that the engine is well serviced & you're using good quality fuel.
Alfa is actually similar, bellow 35mph accelerate hard enough to get the big turbo just spooling up until you hit the desired speed & once above 40mph accelerate as hard as you can without being anti-social. When cruising try to keep the big turbo from spooling up.
