It’s more about engine wear and fuel saving. In days of old, when knights were bold and toilets weren’t invented they used to advise people to change down gears esp when going downhill. It means the car brakes using the engine rather than the brakes. If you were on a steep hill, there is wisdom in this, you get a more controlled descent. On a less steep hill though you can just coast in neutral allowing gravity to propel the car and use the brakes to bring you to a controlled halt.
This will mean that you will wear the brakes more than you would otherwise, but when a set of brake pads cost maybe £50-£80 and a new engine costs £1000s then it makes sense.
Equally any time you are on a flat road and can see you are going to need to stop for a junction or traffic light then again, coasting in neutral and using the brakes is going to save a little fuel.
The advice was to carry on in the gear you were in, dip the clutch at the end.
The reasoning given was that with modern brakes it is not necessary to use the gears to slow down.
I was taught to be in the appropriate gear at all times, thus in proper control of the vehicle.
I think I may not have been sufficiently clear. I keep the clutch depressed, even when changing down. I don’t usually use the engine to brake; just like to be ready in case I need to set off again.
I was under the impression that a car in neutral and allowed to roll along was out of control…I also change down to control the speed of the vehicle unless in an emergency…
No that’s patently nonsense. What you may be confused with is a car with the engine switched off coasting down the road. That would be out of control.
With the engine running your car is fully functional, including the power steering and brakes. You are no less in control of your vehicle out of gear than when it is in gear.
Using the engine to slow the car rather than brakes is a very bad idea these days. It will ultimately damage the engine.
Brakes will control and slow the car just fine and new brake pads are far far cheaper than a new engine.
Image result for driving in neutral illegal
In addition to safety, the other reason not to coast in neutral is that you will use more gas than coasting in gear. In modern computerized automobiles, the engine can cut off fuel if there is low load or no load on the engine. … Because you are in gear, the wheels will keep turning the engine so that it doesn’t stall.30 May 2014 Downhill in neutral is illegal and dumb, and a lot of drivers … Roadshow: Downhill in neutral is illegal and dumb, and a lot of drivers do it – The Mercury News…
Obviously. But you’re using the minimum amount of fuel because the engine is only idling, which is typically under 1000rpm.
If you cut off the fuel the car engine would stop so something is off in what you say. I’m not referring to those cars with “Stop/Start” technology here.
If the engine is running at all then it IS burning fuel. The engine cannot run without fuel. That being the case the smallest amount of fuel one can use is the minimum to simply keep the engine ticking over.
If you are coasting in neutral the engine still req fuel to be sent to the combustion chambers to maintain idling speed, typically around 1000rpm, if you leave it in gear and lift off the accelerator the computer shuts down fuel so no fuel is being used, the car won’t stall because you are in gear…
Sorry but I’m not buying that for an instant. It is the nature and physical design of an engine to use fuel in order to work.
Cut off the fuel and you cut off the engine. It can no longer be ticking over at that point.
If you believe otherwise you’ll have to provide a source reference.
Let’s suppose you were descending a hill with a low gear selected and no accelerator being used, would there still be fuel injected into the cylinders? I would assume that with today’s engine management systems the fuel would have been cut off because the engine was being used for braking and still under load conditions. Had fuel still been injected into the engine, it would accelerate and not brake. If the vehicle was in neutral though, fuel would be allowed in the cylinders to prevent stalling because there would be no load on the engine. When you push start a vehicle, the accelerator must be used to allow fuel into the cylinders, otherwise, no fuel would be present in the cylinders and the vehicle would fail to start…
I wouldn’t assume that at all. If the fuel is cut off then what you are saying is that all the pistons and valves are still going up and down but with no fuel in them. That surely wouldn’t be good. They are designed to have fuel in them and have the gasses expelled during that movement cycle.
No. If the engine is simply working at idle speed then the accelleration is minimal. Try going into 1st gear on a flat surface, lift the clutch and stay off the accellerator. The car will either stall or slowly creep along the road.
The effort of Idle speed will make little difference going down a hill. The force of gravity will be the issue.
The entire idea of cutting fuel off whilst the engine is still running is flawed.
Stop/Start cars may well cut fuel off, but at the same time they cut the engine off too. Why don’t they keep the engine running and just cut the fuel off instead ? Answer because cutting the fuel off would cut the engine off obviously.
If you had a moving car on a downward hill with engine running, ignition on and you cut off the fuel, you would essentially be putting the car into “bump” mode, the thing you do when your battery is flat, bump start.
Running your car in “bump start” mode for any significant period of time isn’t going to do it any good imo.
A quick Google search would show you that most computers cut off fuel to the engine when the car is in overrun (ie driven by the transmission) There is even an overrun cut off valve.
…I just know it works…