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-   -   ARTICLE: How to get the maximum Fuel Efficiency (https://www.team-bhp.com/forum/owning-car/17748-article-how-get-maximum-fuel-efficiency-39.html)

I guess getting it checked again by Tankfull to Tankfull method should be the first thing to do, and then getting it checked with Hyundai Service would be a way to go.

My neighbor's i10 gives him 10+ figures with 100% AC on always and that too in Bangalore ORR traffic. I am not sure if Kolkata traffic is similar but ORR traffic is bumper-bumper all the way. He usually does Sarjapur to Marathalli everyday.

I am sure there is some error in calculation ; such FE figures can't be true unless the traffic moves at such a pace that your AT shifts only to gear no.2 at best.

Maybe you could take the car on a highway, run at 80kmph and then judge ; a lot of fuel will be spent but I think is would be worth it.

I would have expected 100%AC figures even in bumper to bumper traffic to be no worse than 10-11kmpl. Our 1.4 Punto, which is a known low mileage car, gives us 10+ with AC on in pretty heavy traffic. Either your calculation is off, or something is wrong.

I dont buy the fact that the volume of fuel from the pump is wrong. They would cheat you upto about 10%, ie give you 900ml against 1L shown. So even with that error you would still be getting a figure lower than your previous AT. So that's of no point at all.

Do a couple more full tank to full tank check, using different fuel pumps to eliminate the fuel pump error, and then see what the result is. If it stays below 10, something may be wrong.

Yes I am aware of this method. i10 has a 35L tank. Generally it takes upto 31L after the fuel light comes up. If you roll the car a little bit, it will take couple of litres more but I prefer to stop at the auto cutoff. I got this habit
from US I guess where there is generally a sign at the gas stations to not to top off.

So is my experience. The car was vacuumed, soaped, washed and underbody anti-rust coating was done in front of me. It went inside the shop for a while and came out in 10 minutes - not sure what was done during that. I think it would have been a casual routine check.

It took 31.27 L fuel with tripmeter showing 233.6 KM. It is not an AT, it's a stick-shift.

I will take all your suggestions, run a few more iterations and post back.

Even I know a friends i10, just 6 months old, giving 9-10 mileage in my home town. Rip it, and he says, he can literally see the fuel level dropping.

In any case, I don't see a particular reason for the mileage dropping for a new mpfi car. May be a blocked air filter. Also, how is the idling (rpm), do you smell the excess petrol?

Hi folks,

Adequate ground clearance is essential to avoid scraping of a car’s bottom. Users on this forum would tend to generally converge on a number of 170 mm of average GC for a normal sedan. (Let’s not debate the number though!) At the same time, the decision of GC is affected by the need to ensure adequate handling of the car, which is adversely impacted with an increase in GC. Of course, there are other secondary factors like wheelbase and suspension setup that further affect the decision on this.

My question is whether GC affects the aerodynamic drag of a car and thereby its FE. There seems to be little on this either on team-bhp or on the net. I am prima facie inclined to believe that there is no such relationship.

However, my query arises, because I have seen a few cars with amazing handling than usually demanded by most Indians, who decide success of a car. A car like Linea MJD, with its phenomenal handling, could possibly afford to increase its pathetic GC without any unacceptable sacrifice on its handling behaviour. Also, Honda is traditionally known to offer low GC (with the pleasant exception of its upcoming Brio) and is known for segment leading FE figures. Why do these cars come with such a poor GC? Is FE a decision factor while determining the GC? Or is it just that the manufactures assume that most buyers do not bother about this aspect and do not pay enough attention?

I also understand that there are indirect factors, like the need to provide wider tyres with an increase in GC to ensure adequate handling, that can adversely affect the FE. At the same time, the tyres with a bigger diameter can result in higher FE (low rpm for same distance covered). This leads me to a corollary query. You often see cars having different trims equipped with different wheels and tyres. Do such different variants have different GC, and also different FE figures? It would seem so at first glance. But the manufacturer does not specify different GC/FE for such different trims. This means there are only two possibilities

• Either the manufacturer is not telling the whole truth
• GC is equalized through other means. If so, what are these measures?

To sum up, I have the following two queries

1. Whether GC has any effect, whether direct or indirect, on a car’s FE? If yes, what are these effects?
2. Do the different variants of a car having different tyres & and wheel sets have different GC? If so, why do manufacturers do not specify it? Also, would such two variants would have different, even if marginal, FE figures - on account of GC and/or differing wheel sets?

Let me now step aside and make way for knowledgeable views.

I live in Mumbai and have been getting abt 9kmpl while driving mostly in the suburbs.

I have read a lot about cars giving the best return if driven between 70-80 kmh and decided to test this while on my recent trip to Pune. Between the HPCL petrol pump on the way to Pune and the IOCL petrol pump on the way back, I travelled 234 kms and on refilling at IOCL I realised I had just managed getting a mileage of 17.84 kmpl !!

I had tried not to exceed 80kmh and only during a few attempts to overtake did i probably exceed the speed and touch 90kmh tops.

Supremely impressed with the results. But i must admit it was a pain to drive at such slow speeds on an empty road. post refilling at IOCL I began to enjoy my driving when I was between 120-140 kmh :)

Yes for ques no 1. Reasons? Don't know enough.

For ques no 2. Manufacturers do not specify anything as the difference is only minimal. They also take us for granted perhaps.

In case of Etios, see below the difference between different variants having different rim/tyre sizes (as calculated on www.1010tires.com):

Pl. note that the difference in radius (wouldn't that also be the difference in GC?) is over 10 mm, which is rather substantial.

Yes, perhaps.

From my personal experience I can say...
a. The bigger dia of the tyre definitely contributes to better fuel efficiency. When I changed the tyres of my Indica from 155/70 to 175/80, the FE jumped by a phenomenal 20%.
b. With a wider and bigger dia tyre, the increased ground clearance contributed to safety by easily overcoming the numerous speed breakers all over the country, apart from giving the car a firmer grip on the road, doing away with the need for a spoiler at high speeds. Earlier, beyond 80 KMPH, the car would simply go waving from side to side ; now even beyond 100, there were no shakes...
c. Of course, the strength of the axle plays a major role in long term effects of this on the overall reliability. The increased rolling has to be acceptable to the axle dia and material ; otherwise, the extra radial load would cause axle break-down very fast. For the manufacturer of the car, this would entail extra costing and hence they do not advocate this.
d. See the tyres of all hi-end cars. The bigger tyres lead to better performance all around with rim dia as much as R19 and beyond.
e. Volvo buses are a classic example of this technology.

I am wondering whether the bigger tyres contributed to a better driving style which resulted in better FE. Did it sit better on the road and hence you could drive more smoothly. Also, with the better GC were you able to drive over the worse road better and thus not keep accelerating and braking as much as before when you were worried about the bottom of the car scraping.

Wouldnt larger tyres have a larger footprint (which leads to better grip I suppose)? Therefore with the larger footprint, wouldnt your rolling resistance be higher?

My two bits. I changed my engine oil to Mobil 1 in the last servicing of my car (Alto lxi). Marked increase in FE. Earlier it used to be around 16 kmpl in the city with the Ac off (in the winter). This winter its gone up to 18.5 on a tankfull to tankfull method. Am wondering though, if the higher cost of the synthetic oil is worth it?

Here's a calculation:

Running on mineral engine oil- FE = 16 kmpl (approx) (with Ac off and in the city)
Price of premuim petrol (Power, Speed, etc) in Delhi- Rs 69 (approx)
Running cost per km= 69/16= 4.31

Cost of changing to Mobil 1- Rs 3000 (including flushing, etc)


Running on synthetic engine oil- FE = 18.5 kmpl (approx) (with Ac off and in the city)
Price of premuim petrol (Power, Speed, etc) in Delhi- Rs 69 (approx)
Running cost per km= 69/18.5= 3.73

Saving per km= Rs 0.58

Therefore, I should be able to break even on the cost of the engine oil change a little over the 5K mark [3000/0.58= 5172 km (cost of oil change divided by the saving per km)]

Given that according to general consensus and the gurus here, synthetic oil is changed every 7.5K - 10K kms, I guess this would be a good argument to shift to synthetic oil to increase FE.

Am not taking into account the other advantages of synthetic oil.

My two bits :)

agree with misquitas on the first service thing for the i10. They just clean & wash the car and return it back to you. The second service is when the Oil change, filter change.

@sbiswas: So unless you have not mentioned anything that would make them retune the engine or ECU there should be any drop in the FE against to what you use to get before the 1st service.st service.

Interesting.
You know, I made it a practice to use a much better grade of engine oil than what service stations normally use for replacement, hence I carry my own can of oil.
In my 93 model M800, I used Castrol GTX right from the start( i.e, from the time I bought it 2nd hand, @ a speedo reading of 73,000 ) & switched to Castrol Magnatec as soon as it was launched.
I'm very regular with engine oil/oil filter changes.
As a result of this, the 800's engine is still silky @ 1.5 lac kms.
Starting is easier in the Delhi winters etc but I never noticed better mileage as a result of using a higher quality of oil than prescribed.
I use the same practice wrt my 97 model Esteem.
I wonder why owners manuals always seem to recommend the "bare minimum" grade of oil, when, for a few Rs more, you can get much better protection/engine life.
Strange.

The logic from an OEM point of view is very simple. The bare minimum grade is cheaper than a better oil. Therefore, it costs less for the initial manufacture, and it keeps service costs down. Both are better from a financial perspective. The first for the OEM and the second for the customer.

For an OEM, if they save say 1,000 rupees a car, that is a huge amount. Multiply that into 100,000 cars manufactured and the amount saved is 100,000,000. That is 10 crores. Which is why they skimp on so many essential items like say a passenger side rear view mirror, oils etc.

For the average Indian customer, that saving of 1,000 rupees per service seems to be important. I can't explain it, but when the first question most people have is "What mileage does your car give you" I guess the OEM's are tapping into that mentality. Only people that are concerned about their cars, and those that are far sighted (more expense now equates longer vehicle life and overall lesser expenditure) go for better quality oils. A small minority of customers in this country unfortunately.