[msprabhakar]

Originally Posted by venkatrx

1. Is 'auto climate control'[vxi] more fuel efficient than 'normal ac' [lxi]? if yes how? if not why?

Yes, marginally (~3%) because the AC is not allowed to overcool...

Originally Posted by venkatrx

2. does 165/80 tyres more fuel efficient than 185/65 tyres?

Technically... no, since contact area is same if inflated properly. The difference is only in ride Q (80>65) vs handling (185>165)...

Originally Posted by venkatrx

3. some times AC gives some strange smell, i have observed this in both 'fresh air' mode as well as 'recycle air' modes. any clue what it is?

I think this has been answered in some other thread by somebody else. Possible reason: Underbody anti-rust coating... bear with it for some time. Either it will go away or you'll get used to...

Originally Posted by venkatrx

4. have you upgraded to 100/90 lights.....i find 60/55 stock lights pathetic. any other solution other than 100/90.

Actually Baleno's stock lights are its Achilles' heel. I've upgraded to HID Xenon.

Originally Posted by venkatrx

5. at what speed we get maximum FE (in bikes i remember 55 to 60 kmph was marked as economy zone, so what about balano?)

Forget thinking about speed... think rpm. Theoretically, FE is maximum at rpm of max torque @ highest gear(for Baleno it's 3000 rpm @ 5th). Practically, you need to take advantage of 'flat' torque region and upshift as quickly as possible @ ~1500 rpm. Maintaining your speed at highest possible gear (under your safe driving conditions) to ensure that your rpm stays in 'flat' torque region (~1500-3000 rpm) will give you the max FE. For Baleno, this approximately translates to 55-115 kmph range on flat and smooth roads.

Hope you're gyan-ed well enough...!

[msprabhakar]

Originally Posted by venkatrx

...Also to be noted is that Baleno FE is a little skewed, 7 have voted for 10 kmpl, 3 have voted for 11 and even though 12 kmpl is the peak. Baleno FE distribution doesn't seem to follow the normal distribution curve...

If the class intervals are finetuned, even this poll might approximate a normal distribution...
For example, <9 (0); 9-10 (8); 10-11 (10); 11-12 (19); 12-13 (?)... throws a better light, yet 12+ is in a black box...

Considering the sharp increase in frequency at 11-12 range, and assuming 12-13 would not have produced a higher frequency (say around 25), it's fair to conclude that Baleno's city FE falls somewhere in 11-12 range.

Good poll... good insight... thanks!

[venkatrx]

Originally Posted by msprabhakar

Actually Baleno's stock lights are its Achilles' heel. I've upgraded to HID Xenon.

which brand did u buy, how much does it cost, is this too good ? is warranty avaiable in india?

Forget thinking about speed... think rpm. Theoretically, FE is maximum at rpm of max torque @ highest gear(for Baleno it's 3000 rpm @ 5th). Practically, you need to take advantage of 'flat' torque region and upshift as quickly as possible @ ~1500 rpm. Maintaining your speed at highest possible gear (under your safe driving conditions) to ensure that your rpm stays in 'flat' torque region (~1500-3000 rpm) will give you the max FE. For Baleno, this approximately translates to 55-115 kmph range on flat and smooth roads.

How old is ur baleno?
You say that if i drive between 55 to 115 kmph in 5th gear, the FE shouldn't change !!
whats the FE you have acheived in city / higway? (with / without ac)

Hope you're gyan-ed well enough...!

Thanks MSP,
Great Gyan, keep it flowing.

[venkatrx]

Originally Posted by msprabhakar

Forget thinking about speed... think rpm.

When i asked the saleman, whats the rpm meter, he said its just informative....no action to be taken based on that

At the end of the day, we must ensure that we burn as little amount of Fuel as possible in any given situation to get max FE. Please confirm if the below understanding is correct?

+ Fuel consumption is directly proportional to 'rpm' and '% of accelerator pressed'.

+ Clutch should be used only to change gears and should not be used to avoid vehicle jerks at low speeds.

+ Fuel will burn completely only when the engine is heated atleast to the half-way mark(atleast in the baleno heat meter)

+ I observed that the rpm is the lowest when the vehicle is in neutral gear. So it must be a good idea to shift to neutral when we are about the come to a stop signal.

MSP, more gyan on this please...

[supremeBaleno]

Originally Posted by venkatrx

When i asked the saleman, whats the rpm meter, he said its just informative....no action to be taken based on that.

Well, we can't expect all salesmen to be experts. BTW, one reason for him saying that, could be because the manual mentions gear changes based on the speed (not on rpm).
BTW, you neither need the tachometer (or even the speedometer) to know when to change gears. Think of the engine as something animate, listen to it and the engine sound will tell you when it is time. I don't think most of us change gears by looking at either of the meters - I don't anyway.

Originally Posted by venkatrx

+ Fuel consumption is directly proportional to 'rpm' and '% of accelerator pressed'.

Sounds logical to me. The more you revv, more fuel consumed.

Originally Posted by venkatrx

+ Clutch should be used only to change gears and should not be used to avoid vehicle jerks at low speeds.

Very true. Riding the clutch is a serious no-no. Not only does it lower the FE, it wears out the clutch faster - means expense on replacing it sooner.
Instead of trying to avoid vehicle jerks by using clutch, just downshift to the correct gear.

Originally Posted by venkatrx

+ Fuel will burn completely only when the engine is heated atleast to the half-way mark(atleast in the baleno heat meter)

Not sure about this one.

Originally Posted by venkatrx

+ I observed that the rpm is the lowest when the vehicle is in neutral gear. So it must be a good idea to shift to neutral when we are about the come to a stop signal.

At a stop signal, obviously it is good for your clutch, FE and legs to be in neutral.

[supremeBaleno]

Originally Posted by msprabhakar

Technically... no, since contact area is same if inflated properly. The difference is only in ride Q (80>65) vs handling (185>165)...

MSP, are you sure about this ? Wouldn't 185 tyres have more road contact area compared to 165 tyres due to being 20mm more wide ?

[santosh.s]

Originally Posted by venkatrx

+ I observed that the rpm is the lowest when the vehicle is in neutral gear. So it must be a good idea to shift to neutral when we are about the come to a stop signal.

When you are in neutral, rpm reduces to idling rpm. When the transmition is engaged in any gear, rpm is directly proportional to actual speed of the car (assuming clutch is not pressed). I believe if you release accelerator, fuel consumtion will always be very less irrespective of the rpm. Because the engine is not pushing the car in that state, rather it is being driven by the car's momentum. This results in "engine breaking", which is a good option when you approach a stop signal. If you shift to neutral instead, then you are putting additional stress on breaks (more wear & tear of shoues). I am not sure if it can actually improve FE.

[santosh.s]

Originally Posted by supremeBaleno

At a stop signal, obviously it is good for your clutch, FE and legs to be in neutral.

SB, how does it help clutch? I mean clutch wouldn't be stressed either when its released while in neutral or fully pressed while in any gear, it shouldn't cause any harm in both cases.

regarding FE, does it really make noticable difference if you comare above two situations?

"legs" part is quite obvious, though

[msprabhakar]

Originally Posted by supremeBaleno

...Wouldn't 185 tyres have more road contact area compared to 165 tyres due to being 20mm more wide ?...

Remember, since pressure=weight/ area and since weight of the car is constant and distributed over 4 wheels, contact area theoretically remains constant for any given tyre pressure. Wider tyres means a narrower contact distance front-to-back...

The area of contact does not affect your actual grip of the tyre as much as the coefficient of friction and the load on the tyre... Which is why tyre compounding is a million dollar science...

[Hells Bells]

"At a stop signal, obviously it is good for your clutch, FE and legs to be in neutral."

While it may be a good idea to be in neutral at stop signal, fuel consumption at idling is not the least (as assumed here). Infact, at idling we have a richer fuel-air mixture being passed to the engine and that is why it is recommended that we cut the engine rather than idle at stop signals.

Cheers

[supremeBaleno]

True, but depends on the duration of idling also. If you are idling for less than a minute (or 2mins as PCRA recommends), cutting the engine off would not help in fuel saving.

@santosh.s, you might be right there.

[venkatrx]

Originally Posted by msprabhakar

Remember, since pressure=weight/ area and since weight of the car is constant and distributed over 4 wheels, contact area theoretically remains constant for any given tyre pressure. Wider tyres means a narrower contact distance front-to-back...

MSP, wider tyres means wider left-to-right contact on foot-print.

front-to-back distance on the tyre-foot-print is dependent on the tyre pressure and car weight isn't it?

I think that is why supreme is saying wider tyres, more contact area, hence less FE.

In fact even the sales guys say that if you use bigger tyres FE goes down drastically for this reason....of course u get a great racing car

The area of contact does not affect your actual grip of the tyre as much as the coefficient of friction and the load on the tyre... Which is why tyre compounding is a million dollar science...

This was a bouncer

[msprabhakar]

Originally Posted by venkatrx

...I think that is why supreme is saying wider tyres, more contact area, hence less FE....

Let's say your Baleno weighs 975+78=1053 kg and you prefer tyre pressure of 32 psi (2.25 kg/sq.cm), which translates to a contact patch area per tyre of 1053/(4 x 2.25)=117 sq.cm, which does not change. If you use 185 tyres (18.5 cm), the front-to-back contact is 117/18.5=63 mm; with 175 tyres (mine), it's 67 mm; with 165 tyres it's 71 mm...

[venkatrx]

Originally Posted by msprabhakar

Let's say your Baleno weighs 975+78=1053 kg and you prefer tyre pressure of 32 psi (2.25 kg/sq.cm), which translates to a contact patch area per tyre of 1053/(4 x 2.25)=117 sq.cm, which does not change. If you use 185 tyres (18.5 cm), the front-to-back contact is 117/18.5=63 mm; with 175 tyres (mine), it's 67 mm; with 165 tyres it's 71 mm...

Guys,

MSPs derivation seems correct........but almost every one used to tell wider tyres means....

1. more contact on road(foot print)
2. better grip on road
3. better braking
4. lower FE

But as per MSPs explanation has contradicted point #1.

And points 2,3,4 are due to point #1, if point #1 is false, the rest all would be incorrect

[santosh.s]

venkat, your perceived contradiction is quite valid!! here is my bit of clarification-

Even though the area of contact patch is same, the shape is different which makes a lot of difference. Its "wider" contact patch rather than "more". Wider patch makes the car immune to uneven road surface, so the car becomes better in follwing straight line movement. Steering response becomes more precise (actually sterring wheel also becomes heavier, but most cars have enough power assistance). At the same time, it increases rolling resistance, and hence reduced FE. In short, it improves stability/grip (especially at high speeds) at the cost of FE (but not too much, I guess).

Additionally, wider tyres imply:
-lesser aspect ratio (less tyre flexing, better handling, lesser body roll)
-usually better rubber compound and tread patterns (better traction/braking/grip etc)

All these factors decide pro's (and con's) of upgradation to wider tyres