[Thad E Ginathom]

I've heard some people say it does.

But surely, it is the gas pedal that is controling the fuel supply to the engine, and if it was getting fuel to maintain those revs it certainly wouldn't be slowing you down!

So I say that it doesn't.

And I also say that safety and control is more important than economy!

[anupmathur]

Originally Posted by hot_rod

p.s hey guys pls tell does engine breaking incruse your fuel consumption coz of the rise in rpm?

Engine braking will not increase your fuel consumption. Don't forget you are NOT feeding any fuel to the engine. You are using the engine's compression (and it's effect multiplied through the gearbox) to decelerate.
It is the better way to slow down, as compared to application of brakes. This method should be used wherever possible - by itself and also in combination with the brakes.

[Venkatesh.C]

Originally Posted by esteem_lover

I have seen some bus drivers never use the clutch to shift gears & some others who double clutch. Wonder how ?

bus Drivers use the clutch only for the 1st (both for upshift / downshift) and even when using the clutch the first always grinds in most vehicles.
i used to think that State transport drivers dont care a damn.
Then i saw the mofussil Private bus drivers (KPN etc) also doing the same thing.
I asked them and they said it is a kind of semi auto clutch. I still dont believe if such a thing exists. however even if they dont use the clutch, the 2nd ,3rd and 4th fall butter smooth
A cousin of mine used to drag cars without using the clutch . (i know it can be done in bikes quite easily)
So, im sure it is possible. But i guess we will only end up screwing up the cogs and the clutches and the engine in turn.

[Thad E Ginathom]

Definitely my father could change down as well as up.

But I'm not going to go out and try in nearly-new Swift!

But, I've sometimes noticed that, with this almost-automatic gear changing that almost any half-decent experienced driver will do, one barely dabs the clutch.

I've heard of all sorts of different auto and semi-auto gear changes for buses. As you say, one glance at the buses shows that these drivers don't care anyway!

[kaynmantis]

Down-shift is possible without clutch. Up-shift can vary from difficult to not possible depending on the clutch-gears condition.

Just because its possible does not mean you should use such technique. And don't get too impressed by those bus drivers. Ever noticed, those BEST service trucks in Mumbai. Take a peek at what's behind. They are always full of propeller shafts. That's cause, broken propeller shafts are a common problem due to changing gears without clutch.

[Shan2nu]

p.s hey guys pls tell does engine breaking incruse your fuel consumption coz of the rise in rpm?

There are basically 2 ways of looking at this prob. If you downshift and engine-brake without revv matching, you won't be burning excess fuel but you're eventually gonna reduce clutch life due to the consistant slipping of the clutch that happens when you need to make a smooth downshift.

On the other hand, if you downshift with revv matching (blipping the throttle to match engine the transmission speeds) you're gonna burn more fuel since blipping the throttle uses up excess fuel. But by doing this, you will also be increasing clutch life since there's reduced friction when you release the clutch. This also makes for a safer, smoother downshift.

Your driving style will depend on what you want to preserve more, fuel or clutch.

Shan2nu

[vnabhi]

Originally Posted by vivekiny2k

i have done the gearshifts in two wheelers without clutch. downshift is hard and causes over-revving of the engine. upshifts are silky smooth.

Me too, I've learnt this trick from my dad, and used it extensively on my Lamby and LML Vespa. But I've never tried it on any of the cars I have owned, and think it would be foolhardy to try, moreso when the repair bills could be hefty, should something go awry.

[Thad E Ginathom]

My dad didn't make a habit of it, in fact I only remember him doing it once (to my knowledge; of course I didn't watch his feet all the time in the car!)

This was a special demo.

It was on the steep and twisty roads of Cornwall, UK, too, where much shifting was required.

[druva]

well as an off-topic.. if brake fails, downgrading the gears is a way to slow down. do we use clutch then? though I have no such experience, my feeling is without clutch abruptly changing to lower gears brings the speed down faster!!

[Thad E Ginathom]

...what, without the clutch?

Might strip all the teeth off all the gears in the box. Whether that would leave the car free running, or totally jam the transmission would be a matter of chance.

Not to be recommended --- IMHO.

[Akshay1234]

Originally Posted by druva

well as an off-topic.. if brake fails, downgrading the gears is a way to slow down. do we use clutch then? though I have no such experience, my feeling is without clutch abruptly changing to lower gears brings the speed down faster!!

no way. youll mess up your gears. you have to press the clutch even while upshifting.

[meenakshi]

1) Its advised to press only the brake to slow down, when you are close to the critical speed of the particular gear use your clutch to prevent the engine switching off. If you see a stop sign please leave your accelerator, let the vehicle go on the same momentum you have created by pressing gas pedal earlier. Close to the stop sign you could use clutch to make it to neutral followed by a hand brake while signal. If the signal more than 120 secs you could switch off the engine and start again.

2) 1st gear is not a synchromesh gears means it could be changed only without accelerator. 2nd gear is synchromesh gear but you need wait for a while to give engine particular speed probably you could make your speedo to get to 1100 rpm to change to 2nd gear. Initially you might see speedo, then by practice you must be able to change smoothly. All the while are you driving Alto, Check your clutch for proper adjustments.

3) 2600 kms with a average of 17.75 kmpl (I took 16 kmpl considering measurement variations, averaging) it would cost you 8000 Rs approx. It would be close to 4000 Rs of CNG and 1200 of petrol. You should consider how aggressive driver you are, would you need your boot space, smell of CNG when you are operating on A/C (basically ride comfort), Do you have kids travelling with you for all these miles. In one way it would be adviseable to go for CNG but it depends on your decision as a overall.

Mods: Incase you feel this should be moved to different place ...please

Meenakshi

[Thad E Ginathom]

Can't say about CNG, but re "1", I think we've said several times already in this thread that one should never 'coast', either by holding down the clutch or by putting gear into neutral.

Would CNG make any difference to this golden rule of car control, and if so, why?

[BUXX]

thanks everyone for their replies in this thread!!!
i have stopped "coasting" for long distances, but sometime find it very difficult not to do so! i am trying to change.. !

[im_srini]

I remember a TopGear episode where Jeremy mentions that modern engine management systems are clever enough to identify when engine braking is taking place & drastically reduce fuel injected. He goes on to say that in the cars of today, engine braking uses up less fuel than coasting in neutral !

On the topic of good driving practices, I saw great fuel consumption benefits when I started switching off the engine at traffic stops greater than 60 seconds. Of course, installation of lights with timers in Chennai really helped me out with this scheme. However, a few months down the line, I had to replace my battery because it wouldn't charge ! If the battery went kaput because of the repeated start-stops of my fuel saving regime, I wonder if I really saved anything ?!?