ARTICLE: How to get the maximum Fuel Efficiency

DileepKS · 27th March 2007, 05:36

Here is what I think:

1. If you feel the pressure on the accelerator, you are spending too much fuel. Do that only when needed, like overtaking.

2. If you take the foot away from the accelerator, and you can FEEL the engine braking, you 'had been' going too fast and spending too much fuel

3. If you take the foot away from the accelerator and you can feel the engine jerking (what is the correct term here?), you are going too slow, and you are burning fuel for too long (ie it takes more time to cover the same distance)

Remember, a HAPPY engine is always an FE engine too.

pjbiju · 27th March 2007, 18:47

Simple ways to get more mileage

Avoid peak hour traffic, when you can
While driving on familiar routes, learn where you need to slow down (turns, bumps, pot hole etc.) and instead of using the breaks to slow down, slow down by stopping acceleration in advance. The more you use your breaks, the less your FE is going to be.
Downshift while overtaking, especially from 5th and 4th gears to 3rd gear. This is especially true for petrol cars which have overdrives in the 4th and 5th gears. The roll over time in 3rd gear is less than 4th and 5th gears in most of the cars.
Do not try to overtake every vehicle in front of you (in cities that would mean several acceleration-break-acceleration and finally overtaking) especially if the vehicle in front of you is going at a reasonably good speed.
Keep a reasonably good distance from the vehicle infront to avoid sudden braking. You may be able to slow down by just taking your foot off the accelerator. (This would also save you from the vehicle behind you from ramming into your vehicle)
Switch off your A/C while overtaking - in many cars there is a considerable drop in engine power when the A/C is switched on. Turning them off helps you to accelerate faster.

mithun · 28th March 2007, 05:43

Quote:

Originally Posted by akroy

Infact when u r in 5th gear doing higher speeds(say 100kmph) and remove ur foot of the accelerator, ur fuel is cutoff automatically (in MPFI engines) and engine braking mechanism makes sure that you are not out of control...U will achieve some unbelievable FE by the following practice...

say at 100kmph/5th gear u remove ur foot, let engine braking decrease the speed to 70-80kmph then u again put foot on the pedal and increase the speed to 100kmph and remove the foot again....and continue doing this process...

Cent percent folly !!!

I don't think that this trick will ever work and will give more mileage than cruising steadily at 70-80 km/h due to the acceleration & deceleration involved and the high proportion of air drag that needed to be overcame at 100 km/h when compared to 70-80 km/h.

Also the time required for acceleration to 100 km/h will be more than the time needed for the deceleration from 100 km/h to 70-80 km/h.

akroy · 28th March 2007, 08:49

Quote:

Originally Posted by mithun

Cent percent folly !!!

I don't think that this trick will ever work and will give more mileage than cruising steadily at 70-80 km/h due to the acceleration & deceleration involved and the high proportion of air drag that needed to be overcame at 100 km/h when compared to 70-80 km/h.

Also the time required for acceleration to 100 km/h will be more than the time needed for the deceleration from 100 km/h to 70-80 km/h.

Mithun, Strong statement mate, but you think so but I have tried and tested it...
There is no significant change in airdrag at 80kmph & 100kmph due to the aerodynamic design of car (with windows up)
My statement was of optimization of the FE and at the same time maintain the speeds so that I can cover my distances quickly. (Basically extracting the highest FE and covering the maximum distance)

I agree that u will get the best FE at 60kmph & 5th gear but can u do that in real conditions on a long drive on a highway???? If that is the case, it is better to go in bus which will be shorter in terms of time as well as money !!!

Finally, try it out yourself...I have tried it on all roads and at all speeds, loads and distances and this statement was also based on my experience...

Hope you have understood !!!
Abhi

wizardofid · 28th March 2007, 09:59

You can maximise your fuel efficiency by shifting to the right gear at the right time, but a caveat to that is shifting gears too often is not good either. Shift smoothly, every time you jerk you stress your mechanicals (and your passengers) that much more.

Make sure you dont press the pedal any more than 25% of its full travel at any time, unless your vehicle does not have enough torque as you start off from a lower speed. Get into 'cruise' mode - i.e. 60~70kmph in 5th when you get the opportunity.

Subodh Kumar · 16th April 2007, 18:51

Hi
Is the downsizing of the gear good option during overtaking with efficiency point of view? Recently, during my recent travel from Dehradun to Delhi (fully loaded Petra 1.6), I was forced to downsize when overtaking vehicles at a speed of 80kmph, I was feeling lack of power. I was thinking, I was having problem with fuel or car. But is it because of overdrive? Is that good for efficiency?

drifter · 16th April 2007, 19:19

Quote:

Is the downsizing of the gear good option during overtaking with efficiency point of view

Let the fuel economy go to the dogs when overtaking, downshift as necessary when overtaking, its a safety issue.

Drifter

zenx · 16th April 2007, 20:03

Dunno about the max efficiency, but if you don't want it to dip, don't let me near your car! (I get average to bad efficiency out of all my vehicles - and then they get tested with 10-15% more at the service guys' place - at least the bikes) I don't really drive with a heavy foot all the time, but us the throttle/accelerator to get pretty quick 0-whatever times, shift at high revs, and keep the Honda/Pulsar on the boil

How I envy the 16kmplers....

nik1982 · 17th April 2007, 12:41

[quote=drifter;414808]Let the fuel economy go to the dogs when overtaking, downshift as necessary when overtaking, its a safety issue.

Well said, it would be very difficult to try and overtake in higher gears especially when you do not have much time.

Subodh Kumar · 17th April 2007, 15:22

I just wanted to know whether lowering one gear below while overtaking at high speeds (say 80-90kmph) is normal or not? Is it felt in other cars also particularly 1600 CC enginer? I am new and was surprised when faced this, I had thought 1600CC car should not face this kind of problem. I agree, safety has to be the most important.

Bass&Trouble · 17th April 2007, 16:23

Quote:

Originally Posted by Subodh Kumar

I just wanted to know whether lowering one gear below while overtaking at high speeds (say 80-90kmph) is normal or not? Is it felt in other cars also particularly 1600 CC enginer? I am new and was surprised when faced this, I had thought 1600CC car should not face this kind of problem. I agree, safety has to be the most important.

Deosnt this totally depend only on whethere there is a need to accelerate in order to make the overtake or not? How would it have to anything to do with car/ make/ model/ engine capacity etc?

k36 · 18th April 2007, 13:18

Quote:

Originally Posted by Subodh Kumar

I just wanted to know whether lowering one gear below while overtaking at high speeds (say 80-90kmph) is normal or not? Is it felt in other cars also particularly 1600 CC enginer? I am new and was surprised when faced this, I had thought 1600CC car should not face this kind of problem. I agree, safety has to be the most important.

In all cars, regardless of engine, the highest gear is designed for cruising, keeping FE in mind, and not accelerating. Hence while overtaking you need to shift down.

GTO · 28th April 2007, 10:56

Added the following point to the original article. This has been reported as a very important contributor to fuel efficiency:

Quote:

• The honest petrol pump: Considering the high amount of fuel adulteration and other fuel-industry malpractices, we highly recommend you to choose the right petrol pump. Tampered meters that result in under-filling, misappropriating bills and selling adulterated fuel are some of the most common malpractices. Company-owned filling stations are the best option, though there are some honest privately-owned petrol pumps also. Look around and opt for an honest reputable petrol pump. This alone can account for upto a 10% difference in your fuel efficiency.

amu1983 · 28th April 2007, 11:43

Carpool !!! That's the mother of all the FE related tips on earth. Suddenly, your 15kmpl car become a 30kmpl one (effectively). Check-out ********.com or commuteeasy.com.

appuchan · 14th May 2007, 18:18

Quote:

Originally Posted by akroy

...
There is no significant change in airdrag at 80kmph & 100kmph due to the aerodynamic design of car (with windows up)...

I dont have equipment to try it out. But one thing I can say from Physics is that Air Drag is proportional to the square of the velocity. So if air drag is say 200 N at 80 kmph, at 100 kmph it should be 300+ N. No small amount this. Note that rolling drag is considered as constant across speeds.

27th March 2007, 05:36	#76
DileepKS BHPian Join Date: Dec 2006 Location: Cochin Posts: 137 Thanked: 8 Times	Here is what I think: 1. If you feel the pressure on the accelerator, you are spending too much fuel. Do that only when needed, like overtaking. 2. If you take the foot away from the accelerator, and you can FEEL the engine braking, you 'had been' going too fast and spending too much fuel 3. If you take the foot away from the accelerator and you can feel the engine jerking (what is the correct term here?), you are going too slow, and you are burning fuel for too long (ie it takes more time to cover the same distance) Remember, a HAPPY engine is always an FE engine too.
	(1) Thanks

27th March 2007, 18:47	#77
pjbiju Senior - BHPian Join Date: Apr 2006 Location: Pune Posts: 1,357 Thanked: 1,092 Times	Simple ways to get more mileage Avoid peak hour traffic, when you can While driving on familiar routes, learn where you need to slow down (turns, bumps, pot hole etc.) and instead of using the breaks to slow down, slow down by stopping acceleration in advance. The more you use your breaks, the less your FE is going to be. Downshift while overtaking, especially from 5th and 4th gears to 3rd gear. This is especially true for petrol cars which have overdrives in the 4th and 5th gears. The roll over time in 3rd gear is less than 4th and 5th gears in most of the cars. Do not try to overtake every vehicle in front of you (in cities that would mean several acceleration-break-acceleration and finally overtaking) especially if the vehicle in front of you is going at a reasonably good speed. Keep a reasonably good distance from the vehicle infront to avoid sudden braking. You may be able to slow down by just taking your foot off the accelerator. (This would also save you from the vehicle behind you from ramming into your vehicle) Switch off your A/C while overtaking - in many cars there is a considerable drop in engine power when the A/C is switched on. Turning them off helps you to accelerate faster.
	() Thanks

28th March 2007, 09:59	#80
wizardofid BHPian Join Date: Feb 2007 Location: Bangalore Posts: 207 Thanked: 6 Times	You can maximise your fuel efficiency by shifting to the right gear at the right time, but a caveat to that is shifting gears too often is not good either. Shift smoothly, every time you jerk you stress your mechanicals (and your passengers) that much more. Make sure you dont press the pedal any more than 25% of its full travel at any time, unless your vehicle does not have enough torque as you start off from a lower speed. Get into 'cruise' mode - i.e. 60~70kmph in 5th when you get the opportunity.
	(1) Thanks

16th April 2007, 18:51	#81
Subodh Kumar BHPian Join Date: Jun 2006 Location: Noida Posts: 30 Thanked: 2 Times	Hi Is the downsizing of the gear good option during overtaking with efficiency point of view? Recently, during my recent travel from Dehradun to Delhi (fully loaded Petra 1.6), I was forced to downsize when overtaking vehicles at a speed of 80kmph, I was feeling lack of power. I was thinking, I was having problem with fuel or car. But is it because of overdrive? Is that good for efficiency?
	() Thanks

16th April 2007, 20:03	#83
zenx Senior - BHPian Join Date: Oct 2004 Location: Bangalore Posts: 1,161 Thanked: 158 Times View My Garage	Dunno about the max efficiency, but if you don't want it to dip, don't let me near your car! (I get average to bad efficiency out of all my vehicles - and then they get tested with 10-15% more at the service guys' place - at least the bikes) I don't really drive with a heavy foot all the time, but us the throttle/accelerator to get pretty quick 0-whatever times, shift at high revs, and keep the Honda/Pulsar on the boil How I envy the 16kmplers....
	(1) Thanks

17th April 2007, 12:41	#84
nik1982 BHPian Join Date: Mar 2005 Location: MUMBAI Posts: 90 Thanked: 2 Times	[quote=drifter;414808]Let the fuel economy go to the dogs when overtaking, downshift as necessary when overtaking, its a safety issue. Well said, it would be very difficult to try and overtake in higher gears especially when you do not have much time.
	(1) Thanks

17th April 2007, 15:22	#85
Subodh Kumar BHPian Join Date: Jun 2006 Location: Noida Posts: 30 Thanked: 2 Times	I just wanted to know whether lowering one gear below while overtaking at high speeds (say 80-90kmph) is normal or not? Is it felt in other cars also particularly 1600 CC enginer? I am new and was surprised when faced this, I had thought 1600CC car should not face this kind of problem. I agree, safety has to be the most important.
	(2) Thanks

28th April 2007, 11:43	#89
amu1983 BHPian Join Date: Feb 2007 Location: Pune Posts: 144 Thanked: 0 Times	Carpool !!! That's the mother of all the FE related tips on earth. Suddenly, your 15kmpl car become a 30kmpl one (effectively). Check-out ********.com or commuteeasy.com.
	() Thanks