When it comes to saving fuel in an automatic car, it's not typically about selecting a single specific gear number (like 5th or 6th) as the universally most fuel-efficient at all times. Instead, fuel efficiency relates to how you use the gears in different driving situations.
Based on the provided reference, the most fuel-efficient way to manage gears in an automatic car involves specific actions during deceleration and when stationary.
Fuel-Saving Gear Techniques
According to the information provided, the most fuel-efficient approach involves:
- Leaving it IN GEAR when decelerating.
- Putting it IN NEUTRAL when at a stop.
Let's explore why these techniques help conserve fuel.
Decelerating in Gear
Staying in gear while slowing down (e.g., approaching a red light or coasting downhill) allows the engine control unit (ECU) in many modern vehicles to cut fuel supply to the engine. The momentum of the car continues to turn the engine via the transmission, providing what's known as engine braking, and no fuel is injected.
- Benefit: Zero fuel consumption during the deceleration phase until the engine speed drops near idle.
- Contrast: Shifting to neutral while decelerating means the engine needs a small amount of fuel to continue running at idle speed.
Practical Tip: When you see a red light ahead or traffic slowing, ease off the accelerator but leave the transmission in Drive (or your current gear). Let the car naturally slow down while in gear.
Being in Neutral at a Stop
When your car is stopped, say at a traffic light or in heavy traffic, shifting the transmission into Neutral reduces the load on the engine.
- Benefit: The engine requires less fuel to maintain idle speed compared to staying in Drive (or another forward gear) where the transmission is still engaged and creating a slight load, even with the brakes applied.
- Modern Cars: Some newer vehicles have "Idle Stop-Start" systems that automatically turn the engine off when stopped in Drive, achieving maximum fuel savings at a standstill. If your car doesn't have this feature, shifting to Neutral manually can help.
Practical Tip: When you anticipate being stopped for more than a few seconds (e.g., at a long traffic light), shift the car into Neutral. Remember to shift back to Drive when you are ready to move. Always engage the handbrake if stopping on a slope or for extended periods.
Summarizing Fuel-Saving Gear Usage
The reference highlights two key scenarios for optimizing fuel use related to gear selection in an automatic car:
| Situation | Fuel-Saving Action | Why it Saves Fuel |
|---|---|---|
| Decelerating | Stay IN GEAR | Modern ECUs cut fuel supply during engine braking. |
| At a Stop | Shift to NEUTRAL | Reduces engine load compared to being in Drive. |
By consciously applying these techniques – leaving the car in gear when slowing down and shifting to neutral when stopped – drivers of automatic cars can enhance their fuel efficiency.
