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Old 26th September 2010, 11:39   #451
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Dear all I have something to add here

1) In almost every vehicle there is one particular spot on throttle in which you achive maximum road speed in top gear . Any more throttle dosent improove/increase the road speed proportionally,but consumes more fuel.

This is called as minimum of throttle /accelerator & maximum road speed equation

This is normally around 30% of the accelerator pedal travel.

2) Normally one should not exceed the road speed ( in top gear ) that is 70% of the top speed prescribed by the manufacturer.
For example my Mahindra 540's top speed is recomended as 105 Km/hr. so according to my theory I should not be driving in excess of 70 Km/hr. If I want to have better fuel efficiency .

Sudarshan

Last edited by Sudarshan : 26th September 2010 at 11:40.
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Old 27th September 2010, 10:03   #452
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Originally Posted by chncar View Post
I am curious to know the same. Is it better to move to a higher gear like in petrol, or to run in a lower gear and keep the revs high enough to be in the turbo range?
In any turbo-charged car, whether petrol or diesel, the turbo's spooling will always boost fuel efficiency. Research on your car, know when your turbo kicks in, and upshift just above that point. Example : Tata Manza owners would probably get better fuel economy from upshifting at 2,100 rpms vis a vis 1,700 rpm. Plus, its bad news to "lug" a turbo-charged car.
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Old 27th September 2010, 12:29   #453
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Default Is this strange?

When measuring the FE for my car (2006 Swift ZXi Petrol and the method used is full tank to full tank), I've noticed that the FE is lower if I refill the tank below the quarter level mark to when I refill the tank at around the half level mark or higher. I remember reading somewhere on this forum that the FE is higher if we fill before the half tank mark.
Why is this so? Shouldn't your FE be constant? Is this because of adultration where the impurities get seperated from the petrol and are sucked in later?
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Old 29th September 2010, 09:06   #454
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Originally Posted by SafeDrive View Post
I remember reading somewhere on this forum that the FE is higher if we fill before the half tank mark.
That's hogwash. If we have to go by pure logic, the car would return better FE when it has lesser fuel (and thus, lower weight) onboard.

Realistically, there isn't any difference whether you calculate FE after using up a half tank or full.
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Old 29th September 2010, 09:31   #455
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It makes sense to fill up as soon as half tank mark is reached, or even top-up once a week - in bikes. Reason being, the less volume of air inside the tank, less will be the evaporation loss during hot weather. Because the bike's fuel tank is directly exposed to the elements.

I am not sure if the same logic can be applied to cars as their fuel tank is covered by the body. But just to be on the safe side, I top-up my car too at the half tank mark!

@safedrive
If you use up your fuel fairly quick, you can fill at the low fuel level warning for cars, or reserve for bikes. What I said holds good only when the daily running is low, and a full tank will last a few weeks.

Last edited by Gansan : 29th September 2010 at 09:35.
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Old 30th September 2010, 17:35   #456
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Originally Posted by GTO View Post
In any turbo-charged car, whether petrol or diesel, the turbo's spooling will always boost fuel efficiency. Research on your car, know when your turbo kicks in, and upshift just above that point. Example : Tata Manza owners would probably get better fuel economy from upshifting at 2,100 rpms vis a vis 1,700 rpm. Plus, its bad news to "lug" a turbo-charged car.

Yes, it makes perfect sense to say that turbo's spooling will always boost fuel efficiency. And why won't one make full use of turbo if it's fitted in the car! I am surprized though how Tata has come to the recommended speed limits for each gear for optimum fuel efficiency. The sticker and manual in my car says I should be at 70kmph in 5th gear. That's an RPM of about 1500. Does not seem right to me so I drive by RPM than that sticker. Try to keep my Manza at an RPM of about 2k. And boy, it's fairly quick at that point
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Old 30th September 2010, 22:46   #457
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Originally Posted by ramkris View Post
Toyota has come up with this following methodology to get maximum mileage and track it on their website A Glass of Water - SE

Gave a try with my iphone app, but couldnt login. YMMV.
Don't ever try this stunt. the whole focus will be on the glass and water in it and not on the road and the surroundings. very dangerous according to me.
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Old 1st October 2010, 19:54   #458
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I am afraid Toyota has nothing to do with this. It could have been an unscrupulous way to attract customers.

The facebook entry says..

"To make the challenge more fun you can download the app ”A Glass of Water” for your iPhone. It reacts to your driving as if you had an actual glass of water on your dashboard; accelerate too fast or brake too sudden and you will spill water. It also shows your route on a Google map, distance, driving time, average speed, idle time and water spill in centilitres. Of course you can participate in the 10%-challenge without the app and register your results manually."

********

So, the iphone allpication rather stimulates the water in the glass. No need to put actual glass of water on the dash. If your style of driving is such that the water doesn't spill at all , you will definitely get a better fuel efficiency. :-)

Murthy
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Old 17th October 2010, 12:19   #459
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Quote:
Originally Posted by amit1234singla View Post
Yes, it makes perfect sense to say that turbo's spooling will always boost fuel efficiency. And why won't one make full use of turbo if it's fitted in the car! I am surprized though how Tata has come to the recommended speed limits for each gear for optimum fuel efficiency. The sticker and manual in my car says I should be at 70kmph in 5th gear. That's an RPM of about 1500. Does not seem right to me so I drive by RPM than that sticker. Try to keep my Manza at an RPM of about 2k. And boy, it's fairly quick at that point
Firstly I confess to not reading the entire 31 pages. If somebody has already come up with this please ignore.

I firmly believe that every car has a SWEET SPOT. At this RPM the combination of Driveabilty or Maneuvering, Control and NVH are the best in the entire range.

It takes carefull observation during the initial period to find it.

Another method is to define for yourself a Low RPM Limit and a High RPM Limit and always stay within the two.

Eg 1.) Innova 2100-2500 is the best range for me and the sweetest spot at 2300. At the upper limit of 2500 my speed in fifth gear would be between 85 and 95, depending on the Laden Weight and gradient of the road. This is similar to what GTO suggests in his opening post. Fuel Efficiency :11.5 kmpl/city, 13.5 kmpl/Highway. Tires (OE) have done 67000km and good for another 10K.

Eg 2.) Octavia is still under observation, but I feel the range is a bit more varied between 1700-2200. FE of 15kmpl/city and 19kmpl/highway.

Please feel free to comment.
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Old 4th November 2010, 09:49   #460
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Default Defensive driving leads to low fuel efficiency?

I have been reporting somewhat low FE on my ANHC AT. I also realize that I did not get very good FE figures from any of my previous cars. I have tried to look in to my driving style but could not think of anything wrong (I dont rev up, drive with light foot, use engine breaking as much as possible and drive in moderate speeds)

Recently I went on a long drive and took a driver along. Driver did all the driving after the fill up. After the 400+ kms of journey, the FE showed good 2 kmpl than what I normally get!

This got me thinking about what the other driver has done differently and this is my observation:
He was driving without slowing down as much as possible. If he sees someone trying to intrude in to the lane, he would honk continuously but not slow down.
Even if he sees a crowd beginning to cross the road, he would honk, flash the light and scare them but never tried to slow down or give way.
At times, he has made his way between two vehicles on a 2 lane road.

Now, compare this with my driving style, which is totally 'defensive'.
I would slow down with any hint of someone intruding in to my lane. I slow down at every junction. If I see people who are ready to cross the road I will slowdown and allow them to cross.
Defensive driving style does make you to slow down and accelerate constantly and has impact on the FE.
But I would strongly suggest this approach compared to the dangerous driving style the hired driver was adopting. Sometime it is alright to sacrifice FE.
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Old 4th November 2010, 10:52   #461
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^^
May be the 'longish drive' had a bigger impact on the better FE than 'aggressive' driving.
Also do consider reduced braking here based on the driving style.

OT - FE aspect aside, the way you described that driver's style, he needs to be kicked out, soon (for the sake of the people on the road as well as your car).
That is no way to be driving on a public road, that too on your new car !!!
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Old 4th November 2010, 11:30   #462
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Originally Posted by jigbarai View Post
^^
May be the 'longish drive' had a bigger impact on the better FE than 'aggressive' driving.
Also do consider reduced braking here based on the driving style.

OT - FE aspect aside, the way you described that driver's style, he needs to be kicked out, soon (for the sake of the people on the road as well as your car).
That is no way to be driving on a public road, that too on your new car !!!
I have been having these long drives myself, but the FE I get is usually 2 kmpl less then what this driver managed.
I hired this driver just for a day. It is very difficult to change them (it is not just this driver, but most of the drivers who drive travel vehicles)!
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Old 1st December 2010, 11:47   #463
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Have seen traffic parting for some drivers, like the sea parted for Moses!
Had a driver while in Pondicherry, who was not at all rash, and never braked hard at the last moment.He did not use the horn much. In the city, he never exceeded 50 km/hr speed limit. He used to drive at a steady speed and traffic seemed to part for him!

Having got my first driving license in the US,am a defensive driver. For the twelve and half km drive to the office, I used to take almost five minutes more than him.

Yes, he used to get a better FE (approx 10%)

I think that it is a kind of traffic sense that enables some drivers to maintain steady speeds matching the traffic, so that they minimise acceleration and deceleration, leading to better FE. Whenever I have tested a driver for hire, have always watched how often he uses the steering wheel. A good driver will not be constantly making steering adjustments.
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Old 1st December 2010, 12:57   #464
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Quote:
Originally Posted by Fiddler View Post
Eg 1.) Innova 2100-2500 is the best range for me and the sweetest spot at 2300. At the upper limit of 2500 my speed in fifth gear would be between 85 and 95, depending on the Laden Weight and gradient of the road.
Please feel free to comment.
At 2500 rpm in 5th gear you would be at one speed only. either 85 or 95 or somewhere in between, irrespective if your car load /gradient. unless you had a slipping clutch
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Old 1st December 2010, 13:06   #465
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@ mgh ,I will call it a skill of navigation to what you are calling. People like him ( the said Driver ) 'read ' other peoples/vehicles behavior & form their own judgement as to how people & vehicles in front of them are going to act ( their stopping,turning,lane changing etc) & then plan how to drive . This gives the result of what you have called as 'traffic parting '

Many people just learn to drive ( operate the machine ) but neglect this part of driving skill. I think this is an art & some are really masters & also have good command over their vehicles . so they drive more effortlessly ,in respect to car & get maximum milage.

Sudarshan
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