A while back I suggested playing with the throttle. I've stopped doing this because I was finding it hard on my transmission.
Anyways, we all want to find the most fuel efficient means to accelerate, but how do we measure that? Well, on the
EPA's page to improving fuel economy they get their info from Energy and Environmental Analysis, Inc.,
Owner Related Fuel Economy Improvements.
The information regarding acceleration and fuel economy is quite interesting. They found that on some cars that are designed for speed, aggressive acceleration (which they measure in mph/second) can be more fuel efficient than relaxed acceleration.
Anyways, the government tests (which the old numbers are based on) are done at 0.89mph/second city and 0.38 highway (or 1.43km/h/s average city acceleration and 0.61km/h/s highway). Or for more practical terms, when accelerating, if you count 5-6 to 13 seconds your speedometer should increase by about 5mph or it should take 7 to 16 seconds to increase speed by 10km/h.
I did this at the faster end of the spectrum on my car, and found it somewhat lagging. So I tried increasing acceleration so that every 4 seconds (or about 2.5km/h/s), my car accelerated by 10lm/h and I think I have hit a sweet spot. Also worth noting, this is about 25% of my vehicle's acceleration power, since the max average acceleration is 10km/h/s (0-100 is 9.9 seconds)!!!
So in conclusion, for those of us in automatics at least, figure out your car's 0-60mph or 0-100km/h speed, and try using 25% of that. Then try adjusting that by various speeds to see which ones yield the highest fuel gains.