Originally Posted by awsimons
I'm sorry but implying that a 6-speed transmission is more efficient than a 4-speed because it has "2 more speeds" is uninformed. An apples to apples comparison of two transmissions' highway gas mileage would require each to have the same gear ratio.
I'm not just talking highway, which is a limited view. I'm talking overall. The whole point of 6-speeds or more is to have gear ratio spacing optimized for a broader range of operating conditions and better efficiency. I've seen quotes of 3-5% savings in general just for having 6 gears versus 4.
ZF says their new 8-speed transmission has two big advantages: improved fuel economy and shorter gear steps between cogs, for quicker acceleration and smoother shifts. They claim it's 6 percent more fuel efficient than their old 6-speed.
Plus I remember my 4-speed Contour turning around 2800 on the highway. The Focus is a couple hundred less than that IIRC.