I have long wondered why the auto manufacturers use overdrive transmissions. Wouldn't a high gear that is direct 1:1 be a more efficient transfer of power? So what I see is that a 1:1 top gear with a taller differential would be more efficient that achieving the same overall top gear ratio with overdrive and a lower differential? For instance a .80 ratio overdrive with a 3.55 gearset compared to 1:1 top gear and a 2.84 gear to achieve the same final ratio of 2.84. It would seem the 1:1 with a 2.84 cog would be more efficient because the 2.84 might have less drag and the 1:1 definitely has a smoother power path than the .80 overdrive does.
Comments? Did Detroit just sell us a buzz word here?