http://www.merriam-webster.com/dictionary/overdriveIt is the first definition :-)
The term used correctly describes a very specific condition as C1xRider said- if the output shaft of the transmission is turning faster than the input shaft, it is in fact an overdrive. Most transmissions (I speak generally here and it applies more to older autos then current transmissions in all vehicles) simply locked the output shaft to the input shaft in the highest gear. So if you had a four- speed transmission, you really only had three gears and a 'pass through' coupling that was called fourth gear. The vehicle's overall gearing in high 'gear' was controlled by the rear end ratio exclusively. The along came a manufacturer who actual did use a gear ratio for high gear which gave the drive train designer more flexibility in the vehicle's ratios (a lower rear end ratio for better low gear acceleration but still relatively low engine speeds for highway cruising). The marketing people called it an 'overdrive'.
More recently the term has become used to describe what a manufacturer wants to point out as a high overall gear ratio but they are using the term incorrectly, technically speaking. When the term is used that way it also becomes meaningless because it has no definition and can be whatever the manufacturer wants it to be.
So strictly and correctly speaking, the C-14 does NOT have overdrive. It does have a high gear ratio in sixth gear resulting in low engine RPMs for given highway speeds and that is what they are probably trying to convey from a practical point of view.
In the end, KiPass fixes all of that up and covers us all in a cloud of euphoria anyway no matter what gear we happen to be in at the time, including neutral.
Brian
No. Totally serious. Do you have a link to something or can refer to a book that has the 'proper' definition of overdrive? I'm willing to listen to alternate theories but I need solid references before I change my mind. So far, I haven't seen them.