IMHO, the number of gears does not affect the fuel efficiency. although it is the gear ratios that will determine how often you shift and how fast you go, it is still the manner of driving and load that plays the greatest in terms of determining fuel efficiency. it is still the optimum speed at the right rpm and gear that will determine the fuel efficiency.

btw, bago lang ako dito sa tsikot.. this forum is quite engaging, exciting, and interesting. more power!