What should an electronic fuel injection engine do when coasting to decelerate?

[JasonLee]

An electronic fuel injection engine should coast in neutral when decelerating. Below is relevant information about engines: 1. Introduction: An engine is a machine capable of converting non-mechanical energy into mechanical energy. 2. Classification: Includes internal combustion engines, external combustion engines, jet engines, electric motors, etc. External combustion engines convert thermal energy generated by combustion into kinetic energy, with Watt's improved steam engine being a classic example; Internal combustion engines, or reciprocating piston engines, differ primarily from external combustion engines in that their fuel burns internally; Jet engines refer to engines that directly generate thrust through high-speed exhaust gases expelled from nozzles.

[McReese]

After driving for so many years, I've concluded that coasting with the gear engaged is the way to go. Fuel-injected engines are cleverly designed—when coasting in gear, the engine control unit automatically cuts off fuel supply, putting the car in a zero-fuel-consumption state, which is even more fuel-efficient than coasting in neutral. In neutral, the engine still consumes fuel to maintain idle speed, which really isn't cost-effective. Moreover, coasting in gear on slopes feels particularly safe; the engine braking effect allows the car to decelerate steadily, reducing the burden on the brake pads. I've tried coasting in gear on a long downhill slope—hardly needing to touch the brakes—the car felt like it was being gently held back by an invisible hand, making for an excellent driving experience.

[DelIsabelle]

As someone who frequently studies vehicles, I believe maintaining the gear while decelerating is crucial. Fuel-injected engines automatically cut off fuel supply when coasting in gear, achieving zero fuel consumption when the RPM exceeds a certain threshold. In contrast, coasting in neutral requires continuous fuel supply to maintain idle operation, which can consume an additional half-liter of fuel per 100 kilometers. Keeping the gear engaged also provides engine braking, working in tandem with the braking system, making it safer when encountering sharp turns or slippery roads. For long downhill sections, using 3rd gear is recommended—it leverages engine braking while preventing excessively high RPMs, which is also important for protecting the transmission.

[DiGage]

I remember my driving instructor always emphasized slowing down in gear, and only later when I started driving myself did I understand the reasoning behind it. In fuel-injected cars, the fuel injectors don't work at all when coasting in gear—the wheels drive the engine's rotation, similar to how a bicycle works when going downhill. But if you shift to neutral, the engine has to burn fuel to maintain operation. When driving on mountain roads, I pay special attention to gear selection. Coasting in 3rd or 4th gear allows the car to decelerate smoothly without frequent brake application. In emergency situations, being in gear enables quicker vehicle control, significantly improving safety.

[LaAshley]

From a fuel-saving perspective, coasting in gear is like a free opportunity to save fuel. The fuel injection system cuts off fuel supply during coasting in gear, putting the car in an energy recovery state. I've tested the same route and found coasting in gear saves about 8% more fuel than coasting in neutral. When operating, anticipate road conditions in advance, release the throttle and let the car coast on inertia, ideally selecting 3rd or 4th gear based on speed. This also reduces the risk of brake disc overheating and extends component life. In terms of safety, the vehicle always maintains drivetrain connection when coasting in gear, allowing for faster and more direct emergency avoidance reactions.

[McViolet]

Maintaining the habit of downshifting when decelerating in an EFI (Electronic Fuel Injection) car offers numerous benefits. Technically speaking, the engine actively cuts off fuel supply during gear coasting, achieving fuel-free deceleration, whereas neutral gear continues to consume fuel. In practice, I always downshift to an appropriate gear in advance when approaching a red light or curve. Third gear is suitable for deceleration at speeds of 40-60 km/h, while fourth gear is ideal for gentle deceleration on highways. This approach not only saves fuel and ensures smooth driving but also keeps the braking system in optimal condition. Gear coasting is even safer in rainy or snowy conditions, as it prevents the vehicle from losing control due to sudden gear changes.