[vigsom]

Originally Posted by guruji

My ertiga has crossed 1L km recently and i am observing a drop in mileage these days. now I have to go through quite heavy traffic. how low the fuel efficiency can drop? I am seeing 10Km/l

Ten kmpl is not bad mileage for high traffic driving. I presume your AC is on and you are primarily running no higher than 3rd gear.

A good pointer would be to test some other car(eg. DZire/ Swift), running on the same fuel under similar conditions.

[landcruiser123]

Originally Posted by guruji

My ertiga has crossed 1L km recently and i am observing a drop in mileage these days. The running pattern also has changed....Can any one please help?

Would love if you could clarify the fuel and type and transmission. Those numbers look okay for a petrol MT or AT. They are marginally low for a diesel.
I’d check:
1. Clutch/Flywheel (if the car has a stick shift)
2. Fuel lines/pumps/injectors
3. Tire pressure (Tire health also)
4. Chauffeurs maybe abusing the clutch by driving in the second gear in crawling traffic
5. Air filter
6. Engine coolant levels
7. Check FE be taking it on a short highway sprint while maintaining a constant speed and measuring FE by tank-to-tank
8. Fill from reputed fuel stations

[uditsharma01]

I was stumbling upon Quora and suddenly this question,

"What burns more gas, accelerating as fast as possible to 60 mph (e.g. 10 seconds) or accelerating slowly (e.g. 30 seconds)?"

caught my attention. I am in the impression that linear acceleration is best to get the maximum fuel efficiency. But to my surprise, if you check out the link and answers there, people are in favor of quick acceleration. This is fairly convincing and extremely debatable.

An excerpt from the comments there:

the quicker you get up to speed the less gas it takes to get there. That's all you have to think about, the longer you take to get up to speed the more gas it takes to do so and that is the whole story to it

It'd really interesting to know what fellow BHP-ians have to say about it.

[Thermodynamics]

Both are wrong, accelerating slowly or rapidly.

There is an old classic thread on the topic here (ARTICLE: How to get the maximum Fuel Efficiency), I guess not much to add, just got to be in right gear so that engine is running close to optimum rpm.

[uditsharma01]

Originally Posted by Thermodynamics

Both are wrong, accelerating slowly or rapidly.

There is an old classic thread on the topic here (ARTICLE: How to get the maximum Fuel Efficiency), I guess not much to add, just got to be in right gear so that engine is running close to optimum rpm.

I absolutely agree with the points mentioned in the article. (Been a follower of TBHP for a long time).

On contrary to what's written in the answers on Quora, quick acceleration in cities will also result in more frequent deacceleration. Consequently squandering a lot of fuel.

I was intrigued with the answers there. That's why I thought to start a thread.

[Jeroen]

The Quora article is very different from the TeamBHP thread, I believe.

The latter provides a lot of guidelines on how to drive as fuel efficient as possible.

The Quora article is just a simple debate and subsequent test on how to get up to a speed of 60 km/h in the most efficient way.

So that is a one off, nothing to do with real life driving, let alone driving in busy rural environment.

The point being made is that there is trade off due to time taken to reach that speed. The premises being to accelerate fast, because you get up to 60 mph quickly.

I haven't given it a huge amount of thought, but there is probably some element of truth in there.

To think this through, lets think about the two extremes; Very slow accelerating and very fast aggressive accelerating.

If you accelerate very slowly, it could actually take hours to get up to that speed of 60 km/h. Admittedly, the engine is producing very little power all that time, but it still using fuel for a very long time.

If you accelerate very aggressively, obviously you will get up to 60 mph very quickly. But red lining an engine itself will take a lot of fuel. But only for lets say 10 seconds.

So we have a slow case where we burn a tiny bit of fuel every second, for several hours.

And another case where we burn a lot of fuel per second in only 10 seconds

Gut feeling suggest that the latter one is still more fuel efficient. The most optimum is probably somewhere in between. It is balancing amount of power against time.

Engines run at different efficiencies across their power band. So you need to find a sweet spot, or rather range in the power band that gives the best performance (least absolute fuel burn) to reach 60 mph. It will most likely be different for different cars/engine/transmission, diesel versus petrol etc.

Jeroen

[Sutripta]

^^^
Wide open throttle (reduces pumping losses), but engine turning over slowly (specific fuel consumption figures can pinpoint figures), short shift, or use a cvt! Acceleration will not be brisk, but because of gearing, not throttle position.

Regards
Sutripta

[guruji]

Originally Posted by landcruiser123

Would love if you could clarify the fuel and type and transmission. Those numbers look okay for a petrol MT or AT. They are marginally low for a diesel.

It's petrol, manual. Thanks for the check points.. I am also now suspecting air filter and spark plugs. Will get them checked first. We recently changed the clutch suspecting that as the issue.

[letsgo2016]

Hi team,

I am currently owing Alto 800 (5 years old - 21k run). On last Christmas Eve I planned my Bangalore to Chennai Trip, at BLR I had fuelled at Shell COCO for tank full. Tank capacity is 35 litres.

Reached chennai and Fuel Indicator showed around 60% capacity. (Half tank)

Fast forward to 10 days later today, I was prepping the car for my travel to Vijayawada from Chennai. Went to a recogised COCO IOCL bunk at Chennai and requested for full tank, to my suprise he filled only 22.5 litres. The meter showed 60% fuel consumed before I filled again here.

Now I had a good run of around 400 off kms from Bangalore to Chennai, which included 40 kms run in city traffic in Chennai for last couple of days put together. I wonder how I managed 400 kms in 12.5 litres of fuel ? 90% of these 400 kms were done without AC.

Kindly note I had done my PMS 50 - 5 year servicing done last week and no complaints were there from my end as well as MAS end. It had a regular service and vehicle is all good with no issues whatsoever. Post the service I had done around 40 kms run inside the city for couple of errands.

Please help if there is any cause for concern as I am planning a Chennai Vijayawada trip day after tomorrow

[KA18]

Normally I would be happy to get a good mileage!

But since you are not sure, why not do a couple more tankfuls after every 50-100kms just to check.

[ashwinprakas]

Originally Posted by letsgo2016

I wonder how I managed 400 kms in 12.5 litres of fuel ? 90% of these 400 kms were done without AC.

And I thought I was the only one!

Originally Posted by ashwinprakas

The last fill-up was for around 2k and after the drive I had almost twice the number of bars that was there when I started the drive, so that roughly translates to about 1k worth of fuel to clock about 400km's, which would return a higher figure than what my P220 usually returns, even discounting error by digital gauge and my own calculation the result is still surprising and can put a Duke 390 to shame.

If you check the math it shows that we both got near similar FE when driving the Alto with the AC intermittently OFF.

Now another mind boggler is that I was driving on the hills of Idukki!

This kinda reinforces my notion that this is the perfect transition for bikers, before this I presumed a Rickshaw would be the best bet but after spending close to 5k KM's with the Alto I simply find it to be better suited. Even at its staggering OTR of close to 4.5L it still gives a Rickshaw and Qute a run for their money as it offers better comfort and drivability all the while returning motorcycle level fuel efficiency!

Regards,
A.P.

[Thermodynamics]

Please correct if my understanding is wrong.

If you started with a full tank and the next refill after 400km was 22.5 liter, it means the fuel efficiency is 400/22.5 = 17.8 kmpl

[gkveda]

Originally Posted by Thermodynamics

Please correct if my understanding is wrong.

If you started with a full tank and the next refill after 400km was 22.5 liter, it means the fuel efficiency is 400/22.5 = 17.8 kmpl

Yes, Thermodynamics is right.

There is nothing to worry about.

Full tank is 35 litres.
After 400 kms, the tank consumed 22.5 litres. This means, car has consumed 22.5 litres to run 400 kms.
12.5 litres is left in the tank.

The OP has done a wrong calculation as 400km/12.5 litres

Also, if the meter was showing 60%. (10% more than midpoint) after 400 kms run, then the fuel gauge need calibration. Ideally it should show 12.5/35 i.e, approximately 1/3 of the full position.

[letsgo2016]

Originally Posted by Thermodynamics

Please correct if my understanding is wrong.

If you started with a full tank and the next refill after 400km was 22.5 liter, it means the fuel efficiency is 400/22.5 = 17.8 kmpl

Originally Posted by gkveda

Yes, Thermodynamics is right.

There is nothing to worry about.

Full tank is 35 litres.
After 400 kms, the tank consumed 22.5 litres. This means, car has consumed 22.5 litres to run 400 kms.
12.5 litres is left in the tank.

The OP has done a wrong calculation as 400km/12.5 litres

Also, if the meter was showing 60%. (10% more than midpoint) after 400 kms run, then the fuel gauge need calibration. Ideally it should show 12.5/35 i.e, approximately 1/3 of the full position.

Originally Posted by ashwinprakas

And I thought I was the only one!



If you check the math it shows that we both got near similar FE when driving the Alto with the AC intermittently OFF.

Now another mind boggler is that I was driving on the hills of Idukki!

This kinda reinforces my notion that this is the perfect transition for bikers, before this I presumed a Rickshaw would be the best bet but after spending close to 5k KM's with the Alto I simply find it to be better suited. Even at its staggering OTR of close to 4.5L it still gives a Rickshaw and Qute a run for their money as it offers better comfort and drivability all the while returning motorcycle level fuel efficiency!

Regards,
A.P.

Guys I just realised that I had made a very wrong Mileage calculation. It is just I wanted to find fault on everything just before a long trip which happens now and then. My Apologies

While I do need to check the calibration of the fuel guage as it does show figures wrongly sometimes as I once stalled the vehicle completely 3 months back as the Fuel indicator was showing 30% but it was fully out of fuel.

Either ways I am getting this checked today just to be safer.

Mods, please close this thread

[ashwinprakas]

Originally Posted by letsgo2016

While I do need to check the calibration of the fuel guage as it does show figures wrongly sometimes as I once stalled the vehicle completely 3 months back as the Fuel indicator was showing 30% but it was fully out of fuel.

Actually the Alto has a more reliable fuel gauge than the digital ones I've used on motorcycles.

Granted issues like reading change based on ascend/descend etc are present which are common to all digital gauges but overall the accuracy is quite good.

To the point that If I fill at the time the last bar starts blinking I'd be filling 30 Liters. And depending on trip meter I can gauge FE by dividing the km's done at the time the last bar starts blinking, by 30 i.e if reading is 600kms then FE is 20kmpl etc. Plus I track expenses via the Fuelio App and the numbers do coincide.

Do give Fuelio a shot if you have the habit of filling full tank, it is quite helpful.

Hope that helps.
A.P.