A Family Medical History Filled With Diabetes, Heart Disease, and Cancer. As a young adult, I witnessed my beloved mother, the rock of our family, battle type 2 diabetes and the complications that come with it. She suffered from kidney failure, vision problems, and heart disease. After 33 years of fighting diabetes, she passed away in April of 2002. I miss her dearly.
Generally speaking, overdrive is the highest gear in the transmission. Overdrive allows the engine to operate at a lower RPM for a given road speed. This allows the vehicle to achieve better fuel efficiency, and often quieter operation on the highway.
Such add-on overdrive boxes were available from the 1930s to the 1970s for cars and light trucks. Today, most petrol and diesel cars and trucks come with an overdrive transmission because of the benefit to fuel economy. [citation needed] Overdrive is included in both automatic and manual transmissions as an extra gear (or two in some cases).