[supremeBaleno]

Originally Posted by AjayJoshuaN

When I travel from Chennai to Trivandrum, I usually reach 100km/h and coast in neutral to 80 km/h and repeat this. Sometimes I would reach to 110km/h or 120 km/h and coast in neutral to 100 km/h as needed and repeat this.

And what about the extra fuel you burn everytime to reach 100-120kmph overcoming higher wind resistance? You would instead do better by driving at a steady 80 in top gear. And reach your destination quicker & safer.

Originally Posted by AjayJoshuaN

Unfortunately this cannot be swept away as a myth or fallacy, as I said, because the evidence of not needing to refuel on a journey > 700 km stands out loud and clear.

Not needing to refuel isn't any written-in-stone evidence. It's just dependent on the car, it's engine, it's fuelTank capacity, type of fuel (diesel giving more FE), road/traffic conditions, speed etc.

Your Xylo has a 55L tank. Even at just 13kmpl FE, you could do Tvm-Mas without refueling. What's the big deal here ?

I do KL-Mas 700km runs without refueling on my Baleno1.6 - the tank is 51L, I drive with a/c on always & drive at max speeds permitted by road/traffic conditions ie. in KL it's within 80kmph & on the fine TN roads, anything between 120-140kmph. And this inspite of the KL stretch of 120kms till Kumily being ghat roads that take me 4hrs.

On the fine & plain Tvm-Mas stretch, even with my driving, I could get even more FE. And if I were to drive at 80kmph max, I could even go & return halfway without refueling. And that's on a petrol car.

FE & maximizing fuel/oil use is very dear to me. But there are so many good ways to achieve better FE instead of coasting in neutral, which is unsafe & unproven.

[dhanushs]

Originally Posted by AjayJoshuaN

...
The point is not about how much fuel is consumed when idling versus engine braking. It is more about destroying the work done by the fuel. Engine braking destroys work done by fuel.

Beg to disagree. Engine braking is there, yes, but, not enough to justify coasting. Next time around, try removing your foot off the throttle and not slot it into neutral, and check for FE.

Higher rpm's cause more engine braking. And now, with New Gen engines having electronically controlled valves, there will be NO engine braking at all! Max efficiency.

People who are not used to coasting will definitely "feel" a bit out of control. It needs a bit of getting used to and adaptation.

LOL.. This is like saying driving against the traffic direction will 'feel' risky, but, needs a bit of getting used to.

[Gansan]

The engine and transmission should always be engaged, except while shifting gears. We need the engine for acceleration/maintaining speed, normal slowing down (foot off the accelerator but no brake), braking (engine braking effect supplements the brakes) and resume normal speed after the braking. Some people brake by pressing both the clutch and brake pedals, which is also a very bad practice.

Coasting in neutral takes away all these safety features which the engine provides. In case quick stopping is required while coasting at high speeds in neutral, the reflex or time may not be there to slot into appropriate gear before braking. Braking while in neutral will take a longer distance to stop without engine braking. It is highly risky to coast in neutral on the highways. It will be suicidal on ghat roads. In ghat roads we should descend only in gear, by using the same gear(s) we used for climbing up the hill.

So please avoid that practice. It will endanger not only your car and the occupants, it will endanger others on the road too. Life and limb are more precious than the few litres of fuel one may or may not save by the practice of coasting.

[Mumbaiker]

Not sure if it saves fuel or not, but it is not recommended for sure.
I have had a near miss experience with my wagonR 10 years back. I was so confident, I even switched off the engine to save fuel with my family in the car to show them "see how I can drive even without the engine being turned on".
We reached the bottom of the slope and lo-behold, the brake had no pumping left. I panicked but luckily there was a small bump on the left of the road where I was able to slow down the car enough to get it to a stop without anyone getting hurt.
From that day onwards, I have never tried coasting on any road

[AjayJoshuaN]

Originally Posted by Aroy

As far as I remember, studies were carried out in US regarding this very issue. What was found is that the fuel used while cruising in gear at an optimum speed was much less than fuel used while coasting in neutral (idling).

https://www.popularmechanics.com/car...-fuel-economy/

https://practicalmotoring.com.au/car...can-save-fuel/

The flaw here again is that a comparison is done between fuel consumed during engine braking vs fuel consumed during coasting, which is not what I am referring to.

The distance that the vehicle can travel would be more without engine braking.
If engine braking is used, again the accelerator will need to be depressed in order to make up for the distance lost due to engine braking. So in essence, more fuel would be consumed by engine braking driving style.

Originally Posted by supremeBaleno

FE & maximizing fuel/oil use is very dear to me. But there are so many good ways to achieve better FE instead of coasting in neutral, which is unsafe & unproven.

If this is unsafe and unproven, then why would there be a zero level regen option on EV's to coast?
e.g.

https://youtu.be/hsKQs1p0_oA

[FiatDiesel]

Folks, I think to save fuel or for optimum fuel efficiency manufacturers provide overdrive gears like 5 or 6. In any case in slow gears you can’t coast and even if you do you won’t gain much against the hassle of switching gears.
My view is that driving with gear slotted in is the right approach. To save fuel, have good driving skills which includes
1. driving in right gear as per speed and traffic. Don’t unnecessary speed up or lug the engine.
2 Use clutch wisely.
3. Use brakes however optimise it’s usage with your driving style / skills.

In long run it all becomes part of your reflex’s while driving.

[supremeBaleno]

Originally Posted by AjayJoshuaN

If this is unsafe and unproven, then why would there be a zero level regen option on EV's to coast?

Because for starters, there's a lot of difference between IC & EV engines, especially the transmission part & thus not a valid comparison.

Maybe you could do a fullTank-to-fullTank FE check between your speedingTo120&coastingTo80 method and justDrivingAt80InTopGear during your next 2 Tvm-Mas drives & post data here. That would be more authentic than MID figures or internet info.

FE figures apart, I really find it bewildering that someone can drive 700kms by repeat acceleration to 120, switching to Neutral, slowing to 80 & then repeating this umpteen times.