Cg125 is far better bike as compared to CD 70, but it would be injustice to compare the two because there is a lot of difference in the two bikes as compared to power, etc. definitely the 70cc will consume lesser fuel, but even the fuel average of 125 is not bad, my 03 model gives me around 45km per liter even now, originally it used to give me above 52km per liter, so nothing to worry about the fuel average.