Drive and overdrive are car terms related to the transmission and power train of a car. In modern cars, these two are present in both automatic and manual transmission. By the word itself, overdrive means the top gear of a car. The car will move at a high speed when it is on overdrive. Though the car is moving fast during overdrive, it consumes less gas and exerts less power as cars are built for speed.
It is best to use overdrive on highways as the car is moving most in straight roads. On the other hand, the drive operates at low RPM and is going in a much slower pace compared to overdrive. It is advisable when traveling in the city as the roads are narrower and there are speed bumps and pedestrians. It is advisable to use drive when driving uphill and downhill as it will give you more power and control on inclines.
If you are a race car driver, you probably know about and use overdrive often. People who drive fast need overdrive. There is a difference between overdrive and drive. Overdrive is a gear in the car that is technically higher than drive. It is usually considered to be the top gear. Most people drive in the drive, which is the standard gear to drive in.
However, if you want to accelerate your speed but not use a lot of gas, then people tend to use overdrive when they are in that type of situation. This allows the engine speed to be reduced so that there is not a lot of wear and tear on the engine. Drag racers use overdrive a lot to go fast without ruining their engine because that item in the car costs a lot of money.