[noob]

This is the followup of my previous thread posted about a year ago: https://www.i30ownersclub.com/forum/index.php?topic=15974.0

In the previous thread, I mentioned that the calculated fuel consumption figure was 7.85L/100KM. I don't know why, but according to the calculation I just did, the first year's fuel consumption is somewhere around 8.39L/100KM, and the altogether figure is very close: 8.37L/100KM. This is even worse. I see people with the same car (i30cw auto diesel) having 6.x L/100KM many times, and most importantly, I've never seen a figure as high as mine. Even in my last thread there are people with the same car having 6.x L/100KM and even better (5.x L/100KM). I'm now confused why they said my car's consumption wasn't bad. I think there is a big difference and I'm really disappointed that my car works far less efficiently. I even suspect that a petrol version of the same car runs more efficiently, making the extra $2000 I spent on the diesel engine a waste. My current total mileage is around 22500KM, by the way.

In addition to the high consumption figure, my tank isn't very close to official data (53L). Most of full tank refilling litres are around 44L, so I believe it's around 44L. I haven't been doing the true full tank refilling trick, but I guest the difference isn't big. (Please correct me if I'm wrong.) This has nothing to do with the L/100KM figure. But it makes my full tank driving mileage lower. I've never reach 700KM per full tank. Normally I get about 500-550KM for combined driving. The longest trip with full tank I had was about 630KM. The FAQ has a Quick guide to fuel consumption section which lists full tank driving distance as low as 700KM. My case is not even covered. This is frustrating, too.

The 630KM driving I mentioned above was from Camberwell to Lake Entrance. I guest that it can be considered country driving. Assuming that my tank's volume is 45L, it was 7.12L/100KM. That's worse than other people's urban or combined driving figures. Again, I'm not happy.

I know that I've asked the question in my last thread and many people answered. But I have to ask the same question again: Do you think my car's fuel consumption (completely) normal? And if not, is there anything I can do?

My car will get the 2nd year service soon. I hope there is something which can be done during the service to improve the situation.

Thanks in advance.
Noob

[Doggie 1]

Your fuel tank holds 53 litres, so if you are putting in less than that, it wasn't empty.
I do wonder whether it would be worth getting the trip computer reset (so that it forgets its history), filling the tank up (brimming it) and then going for a long, country drive.
I would be very interested to see what the result is.
My last car (FD diesel manual 5 speed) used to average @ 6.2 l/100 kms.
With the same driving, my GD (diesel manual 6 speed) averages @ 5.0 l/100 kms but in reality, I don't think there is that much difference.
My last car was averaging out the fuel used since new so it takes a long time to change an average, whereas if a reset is done, it starts over again.
I hope this makes some sense.
Bear in mind that yours is an automatic too.

[beerman]

Firstly as identified by DB08 if you are not taking the time to brim your tank, your 44l is a combination of the tank not being empty and the foam of the diesel taking up space. I can assure you that Hyundai did not go to the considerable expense of redesigning a fuel tank just to make it smaller for you, when you run the car to the fuel light and brim it, you will find you use over 53l to fill it.

Secondly I get around 6.2l/100 in my 2010 CW diesel auto, but I smash the highway miles, I spend next to no time stopped in traffic, and cruise on  the motorway, where the killers of economy stopping and accelerating (especially hard)  to resume speed can't get me. If I do spend time in peek hour traffic, my economy falls, for example a week of roadwork delays pushed it out to 6.8/100.

My Wife on the other hand has a MY11 I30 diesel auto. It is, in theory, the more economical of the two, but the combination of her spending time in stop/start traffic, and her heavier foot, cause her to achieve economy closer to yours. When I use her vehicle for my work commute, it undergoes an transformation and provides better figures then my CW.  This reflects our previous experience where her 2003 BA Falcon was less fuel efficient than my 1997 EL Falcon when taking into account our different commutes. Yet when I assumed full time driving of her vehicle  before I traded it, I got better figures than the EL.

I have no doubt if we swapped vehicles, I would achieve my economy in your vehicle, and you would achieve your economy in mine. What was your previous vehicle and what economy did you achieve with that?

It may be beneficial to Google the various fuel economy tests and what they actually test. For example, I was surprised to discover that the Ultra Urban test was done mostly at 80km/h with short bursts at 100 and 120. This is vastly different to a 100 - 110 kmh cruise on the open road.

I don't how you calculated your fuel economy figure for your trip to Lakes Entrance. In any event, the 7.12 l/100 is not far off some of my economy figures for my vehicle (6.2-6.8).

Do yourself a favour, brim the car and take a nice long drive up the Hume, when the fuel light goes on brim it again and see how you go.

[noob]

Thanks you both for your replies.

As far as I know, my car doesn't have a trip computer since it's the basic model (SX). So this is how I calculate the fuel consumption. I keep every receipt (with price and volume on it). I reset the trip meter every time I refill and write down the trip and odo figures right before next refilling. When I want to calculate the fuel consumption, I type in all the volume data and odo figures in Excel. I sum up all the volumes of diesel to get the number of litres I've used. I subtract the final odo figure with the odo figure when I receive the car to get the mileage of all my driving. Then I divide the two numbers to get the fuel consumption. (The trip figures and the odo figures are used to verify that I didn't miss a single receipt. And no, there is no receipt missing.)

I do wonder whether it would be worth getting the trip computer reset (so that it forgets its history), filling the tank up (brimming it) and then going for a long, country drive.

As I said, I don't think my car has a trip computer but I do reset the trip meter every time I refill. And I don't know what a trip computer is and how it works.
Can you tell me how to brim the tank exactly?

I don't how you calculated your fuel economy figure for your trip to Lakes Entrance. In any event, the 7.12 l/100 is not far off some of my economy figures for my vehicle (6.2-6.8).

Sorry, I didn't make this clear. The 7.12 L/100KM was an estimation based on estimated tank volume (45L) and trip mileage (632KM): 45/6.32 = 7.12. Since the tank volume isn't accurate, the result cannot be accurate.

Secondly I get around 6.2l/100 in my 2010 CW diesel auto, but I smash the highway miles, I spend next to no time stopped in traffic, and cruise on  the motorway, where the killers of economy stopping and accelerating (especially hard)  to resume speed can't get me. If I do spend time in peek hour traffic, my economy falls, for example a week of roadwork delays pushed it out to 6.8/100.

This is the exact part which confuses me. Your peek hour consumption is lower than my combined consumption for about 20% and you don't seem to think my car's consumption is unreasonable. Let's do some math here. Since I've driven about 22000KM so far, I'll use this on both your figure and mine. With your peak hour consumption figure (6.8), it uses 1496L of diesel, while with my combined consumption figure (8.37), it uses 1841.4. So it cost me 345.4L more diesel than you to drive the same distance. If the price of diesel is $1.4/L, it costs me $483.56 more than you, in two years. And don't forget I'm using your peak hour consumption figure to compare to my combined consumption figure. 20% difference is huge. I don't understand why people keep saying that it's normal. (BTW, I'm a noob to cars as my forum ID suggests. So excuse me if I have been stupid.)

I have no doubt if we swapped vehicles, I would achieve my economy in your vehicle, and you would achieve your economy in mine. What was your previous vehicle and what economy did you achieve with that?

This is my first car. So there is no previous vehicle fuel consumption data to compare with. I learned driving right before buying the car. So my driving experience is about two years.
I might not be an experienced driver, at least not as experienced as most of you. But I think I'm not bad at driving (at all) and I did learn green driving skills on internet before receiving my car and have been practicing them in every driving. I avoid hard/sudden brakes as much as possible. I rarely (almost never) accelerate suddenly or hard. I predict slowdowns and try slow down the car by loosing the accelerator rather than using the brake as much as possible. I favor low traffic roads even when the distance is (much) longer. I remove unnecessary stuffs from the car. I even tried refilling only half of the tank in the first year to reduce the car weight. I don't think my driving habits are to be blamed for my high fuel consumption. If you know other green driving skills which I don't know and can greatly help fuel consumption, please let me know.

Here are the links to where I learned green driving:

Then I divide the two numbers to get the fuel consumption.

As you said, you cannot expect to get an accurate figure unless the amount of fuel used during the test period is accurately known. This means that the before tank and the after tank must contain the exact same amount of fuel. The easiest way to ensure that is to start and finish with a completely brimmed tank. To brim the tank there is no way other than to dribble in the last several litres until you can see the fuel in the filler neck. It takes patience!

And I quoted your calculation method above just to verify you mean: litres/km*100 = l/100k

In any case, I want to just add my name to those who suggested that it's the driving conditions and/or the driver that determines the economy, not the car. 

Not sure if it was mentioned; pump the tyres up to 38psi. I run mine at 40.

[noob]

Yes, I think litres/km*100 = l/100k is what I mean. The official web uses "L/100km". I think they all mean the same: litres of fuel used to travel 100 kilometres. Please correct me if I'm wrong.

I know that it's not accurate with such a calculation method. But since there are many times of refilling, the error can be lowered to such a situation that it can be ignored. I'll take my case as an example. The sum of distance I've driven is 22362
KM. The sum of diesel used is 1,872.17 litres. By dividing them and multiple by 100, I get 8.37 (1872.17/22362*100 = 8.37). If we take the difference between before tank and after tank into consideration, the maximum possible difference is a full tank, which is 53 litres. By taking this difference into account, the minimum possible litres of fuel used is 1819.17 (1872.17-53 = 1819.17). Now by dividing it with the distance I've driven and multiple by 100, we get 8.14 (1819.17/22362*100 = 8.14). There is a difference between 8.14 and 8.37, but it's small enough to be ignored because 8.14L/100KM is almost as bad as 8.37L/100KM. And keep in mind that I used a full tank as the difference between before tank and after tank, and the real difference can be much much less. I think it should be less than 5 litres, or 10 litres just to be conservative. If it's 10 litres, the result is 8.33L/100KM. It's very close to 8.37L/100KM.

In any case, I want to just add my name to those who suggested that it's the driving conditions and/or the driver that determines the economy, not the car. 

Are you suggesting that it is impossible for an i30cw (or any other cars) to have mechanical/parts problems which cause fuel economy problem?

Not sure if it was mentioned; pump the tyres up to 38psi. I run mine at 40.

I'll check this. Thanks for pointing it out.

[Hati]

In addition to the high consumption figure, my tank isn't very close to official data (53L). Most of full tank refilling litres are around 44L, so I believe it's around 44L. I haven't been doing the true full tank refilling trick, but I guest the difference isn't big. (Please correct me if I'm wrong.)

Here comes the correction: from first click off of the pump, I consistently get almost dead on 10 litres more into the tank. I just tricle it once it clicks the first time. So your tank is indeed the same size as the rest out there 


I don't have time to look at your green driving link, but the factor that effects milage the most is acceleration. Accelerate SLOWLY is the key. Don't let your revs go above 2200 to 2500 tops and you will notice the improvement even on your auto box. I have a manual, so I don't know how low the auto lets the revs drop before it kicks down a gear. I keep the revs between 1700 and 2500 and get just under 6 litres per 100 clicks in city only driving with no A/C. These engines are the happiest between these rev figures. Try it some day 

[Phil №❶]

Are you suggesting that it is impossible for an i30cw (or any other cars) to have mechanical/parts problems which cause fuel economy problem?

No, but high fuel consumption in the order you describe would have other symptoms e.g. rich mixture smell, black sooty exhaust, hunting etc....

[FatBoy]

Hi Noob,

Don't get confused by what the tank can hold and the distance you drive, but by the amount of fuel you actually use to cover the distance.  As others have mentioned, the only way to do this is to brim the tank, drive a decent distance, then brim the tank again.  Then work out how far you have travelled and how much fuel you have used (i.e. the amount you have put in the tank to fill it up again).

Your fuel usage does seem high, regardless.  Where are you getting your fuel from?  I use Caltex Vortex diesel.  I would stay away from places that sell "cheaper" diesel.  Try one of the brand name fuels (BP, Shell, Caltex) and see how you go.

FatBoy

[eye30]

You can, if you don't wish to brim the tank, do what i do.

I wait until the low fuel light comes on and note the mileage.  Put in your fuel, whatever you want, and then when the low fuel light comes on note the mileage.

Of course you have to presume that the light will come on at the same fuel level in the tank each time.
Also, if i'm not actually by  a service station when then light comes on it doesn't matter so long as you use that mileage figure and NOT the mileage when you actually top up.

Divide fuel into miles to get result.

Now i have been doing this for over 1 year and yes i do get variations at each top up but then i do the average over several top ups and this gives a more accurate figure as it takes into consideration all the different driving i may do.

[Phil №❶]

 

[noob]

Thanks all for the input.

@ Hati: Thanks for the tips of green driving. I do accelerate slowly, but not at a level which will block the cars behind me. I'll try 1700-2500. By the way, does 'tops' means 'rpm' and does 'clicks' means 'kilometres'?

@ Phil No.1: My car doesn't have rich mixture smell and black sooty exhaust. What is hunting?

@ FatBoy: Thanks for confirming that my fuel consumption is high. And from my record, I found about half of my fuel came from Coles Express and the rest came from BP, Woolworths and Caltex. Are fuel from Coles and Woolworths cheap? I'll try only the good brands.

There are a few conditions I forgot to mention:

1) Often times (not always), the fuel meter dropped very quickly at the first several kilometers of trips. (By saying fuel meter dropping, I mean the hand of the fuel meter turning counter-clockwise.) The fuel meter dropping usually turn to normal after the first several kilometers. Is it normal?

2) I've also noticed that sometimes, the fuel meter stayed static for a (very) long distance driving while sometimes it dropped very quickly in a (very) short distance driving. Is it normal?

3) Sometimes the engine thus the whole car shaked/trembled quite heavily several times when there was a gear shifting at low gear. Is it normal? And can it be the cause of high fuel consumption?

[FatBoy]

Hey Noob,

Another thought that I have is your driving "technique".  Now, I'm not saying you do this, but a friend of mine noticed high fuel consumption in his car when his wife was driving (when he wasn't in the car).  He went for a ride with her one day and noticed that she had one foot on the accelerator, and one on the brake, AT THE SAME TIME!!  She said if she wanted to go faster, then she pressed the accelerator harder, and if she wanted to stop she pressed the brake harder.

I don't have an auto, but do you have O/D selected? (I don't know if it is possible in the i30, but in my Terracan you can turn O/D off by pressing a button on the gear selector lever).  Are any auto owners able to help with this?

I believe you have come to the right place to see if what you have is normal.  The i30 community will try and help you (we are like that) if we can, by suggesting things that may be wrong.  If you do have serious doubts, go and get Hyundai to have a look at it, be persistent, tell them it's not normal.

Let us know how you go.

FatBoy

[Eureka]

Noob - in my CRDI 5 speed manual, the fuel gauge needle does seem to drop faster or slower over different parts of the fuel gauge.  I wouldn't worry about that. 

The car shaking when it changes gear: surely, that should not be happening.  It could indicate that something is wrong, but whether that would be effecting the fuel economy I don't know.

FatBoy - accelerator and brake at the same time.  Maybe that explains why I see some cars with their brake lights constantly on. 

[dimons]

Noob - I am also an owner of a 2011 i30cw diesel, but manual.  I live in Brunswick and drive mainly short trips to the supermarket, sometimes to nearby suburbs (yes incl Campberwell) and very infrequently longer trips to Canberra and Sydney.

My lifetime economy figure is 7.25 l/100 with most tankful returning around 8 - 8.25 for exclusively inner urban trips. We also run a 4 cyl Camry wagon which gets 14.5 for the same pattern of use.

My experience is that economy improves drastically when the car is taken on a longer run. I average around 5.25 cruising up the Hume highway. As soon as I get back into the inner city it's back to 8's. I put this down to the fact that the diesel hardly gets warmed up on many of my trips. I notice you said your commute is from Camberwell to Fitzroy. I would expect that you are facing the same issue, it's just not going to give good economy under those driving conditions.

I agree with other posters that brimming the tank is the only way to judge economy on a single tankful but these things average out over the 2 years you have had the car so I don't doubt your figures.

Finally if you have a smartphone install an app to track your fuel use. It's easier that keeping receipts. I use Car Care for iPhone but there are others. Good luck Simon

[Phil №❶]

@ Phil No.1: My car doesn't have rich mixture smell and black sooty exhaust. What is hunting?

Hunting is best described as uneven idle, where the engine revs slightly, then slows and repeats the cycle over and over. You would be able to see the rev counter needle rising and falling as well.

From what you describe, you are a victim of other traffic and short trips. Cars use thermal engines and much energy is used by the motor at each start up to reach, operating temperature. While this is happening your computer feeds more fuel to the motor, which increases fuel consumption. This is the period where your temp gauge needle is UNDER the position it sits at normally. Once the engine has heated itself, the cooling thermostat opens and excess heat is dissipated into atmosphere. Depending on your driving conditions, this can take more than 5 minutes to achieve.

Ideally, the true test of economy is a nice country trip where, at 100k's / hr, you should be able to achieve 5.5 to 5.8 l/100k.

Make sure you are in "D" when driving not "3" to get the best economy.

Do not accelerate harshly (except in an emergency), and keep the revs below 2500 - 3000 for the best fuel economy.

[Hati]

Noob: yes, of course, don't hold up other road users but do not floor it either. As slow an acceleration as allowed by traffic conditions. "Tops" means maximum, i.e. no more than 2500 rpm. You guessed the second part correctly


As far as the fuel gauge is concerned, slow is normal, fast fluctuations are not. Mine works like this: when I brim it it goes to the max (past the full mark), and sits there for over 200 km. Nowadays (37000 km in the car) it's more like 250 plus km. By about 400 km it goes down to 3/4 full. Half tank is reached anywhere between 500 and 600, 1/4 tank around 700 to 750 and I get to 800 plus well before the fuel light comes on. This is city only driving.


I don't have a trip computer and I do not trust them anyway, so my figures are purely odo readings v. fuel to brim calculations. The good bit is the data I get is very consistent and shows improvements as the diesel engines runs in.


On the first few tanks I was lucky to get around 700 clicks, partially because of the new car and because of me getting back in a manual and full time diesel driving.


So there you go...

[Lakes]

could not say why your average fuel usage is so poor.
but for myself on my second FD manual CRDi i'm happy as in sydney average on trip pc always showed 5.2l/100k now down the coast it shows 4.8l/100k but i don't double check calculating myself but i don't reset the tc just leave it as is and it shows i'll get 1,200k b4 needing to refill on this tankful.
i was with my friend in his new FD 6 speed CRDi we had to pick up a truck & was getting a lift in his car, no trip pc in his so could not see average but he was revving it to 4,000rpm & giving me wild sensations in the twistys we where flying but that how he has always driven. i would say he would use a lot of fuel too but he does not care. he just love driving it hard

[noob]

Thank you all for the input.

@ FatBoy:

I don't know what O/D is but by googling it, I suppose it's Overdrive. I cannot find official specification about it. But an unofficial i30cw review says: The automatic transmission features Hyundai’s special Hyundai Intelligent Vehicle electronic control, which has a lockup torque converter and overdrive lockout, and adapts to your driving style. I guess Overdrive is automatically used when the computer thinks fit?

By saying "go and get Hyundai", who shall I contact, a Hyundai dealer or Hyundai's official hotline? By saying "be persistent", do you mean if they say it's normal I shall contact them again and again insisting that it's not normal?

Are fuel from Coles and Woolworths cheap?

@ dimons:

Your fuel consumption is just not much better than mine. And since your car is manual, it means your figures can be close to mine. You are the only one person I've met so far to have similar fuel consumption. Do you have any idea why your i30cw consumes (much) more than most of i30/i30cw in this forum and reviews all over the internet? Does it bother you? It bothers me because I actually bought i30cw diesel for its ability to travel 1000KM+ with a single tank.

By saying "We also run a 4 cyl Camry wagon which gets 14.5 for the same pattern of use.", do you mean that this Camry consumes 14.5 l/100? Is it an auto and non-diesel? It's a lot more anyway.

@ Phil No.1:

Do you think I need to warm up the car before driving? I don't do it because in my green driving study, some sources suggested warming up is not necessary and can actually cost more fuel.

I'll have a look an hunting issue. And thanks for the tips.

@ Hati:

When I max the fuel (without brimming), the fuel gauge usually stays there for about 100KM and can go up to 150KM. And 700KM without gauge moving?! I've never achieved that even with a full tank!


A few general questions:

Does "city only driving" mean CBD driving?
Does "inner urban driving" mean CBD driving, or maybe driving only in the suburbs right beside CBD?

[Phil №❶]

No, I don't recommend warming the car in this way. I do recommend gentle driving though, until the temp gauge is moving. If possible, try not to go onto freeway's with a cold engine as this will cause stress to the motor and turbo.

[Dazzler]

Hey Noob.. I like your powers of deduction 

I think your summary of what each member meant is mostly spot on (don't think I've ever seem anyone drill down quite like that before) 

[Lakes]

Noob, would make a difference, what City's CBD your in, i think the true way to measure fuel usage is to time how long the motor is running  & @ what percentage of Throttle  ( like 10% 80% & so on, ) for example if you idle in heavy traffic a lot that would show up as 0% & how many hours at that %. you could compare that way. but as i've had two CRDi manuals now & both got close to the same economy. it's hard to believe you get bad or poor economy cars & good economy cars it's more to do with the driver & driving conditions & how often car serviced. as with Diesel the oil gets thicker the longer you go between oil changes.
 

[beerman]

G'day mate,

just to clarify, my 6.2-6.8l/100 figure is what I get on the highway, the variance comes due to road works (5 nights of delays over a week of night work for example) in the town parts of my drive.

I haven't used Shell diesel much, but the tanks I have used, I have found it to be less economical.

[Aussie Keith]

Our GD auto get anywhere from 7-8+ around town depending on whose driving it and I've seen low 5's on the highway. On average, I'm recording high 7's low 8's for mostly round town driving for a tank. Your results sounds fairly normal for the type of driving you do. Idling in traffic is what seems to really knock the consumption figure about.

[Doggie 1]

I agree about the idling.
In my last car I used to idle when parked a lot more than in this one and it did push the consumption up.

[noob]

Thank you all for your inputs.

After Hati suggest the RPM, I started to pay attention to my RPM. In my last trip to Phillip Island, I noticed that I normally do go beyond 2500. I usually drove between 2000-2500. I only noticed 3-4 times it went beyond 2500 (and below 3000), and they all quickly dropped below 2500. An acceleration I call "hard" normally go as high as 2500. And I don't do "hard" acceleration a lot. So I guess RPM-wise and acceleration-wise, there is no problem with my driving.

And as I said, I try not to use brake as much as possible. Often times, I found other cars beside or in front of me using brake while I don't. (I keep more than 2-second distance and I predict slowdowns/stops.) So I guess deceleration-wise, there is no problem with my driving.

I know most people suspect how I drive mostly. But I don't think there is a problem.

I'd like to present some more RPM data, in case there is something wrong with it.
Cruising at 100KM/h: ~2200
Cruising at 80KM/h: ~1800
Running at 20KM/h without acceleration/brake: ~1000
Holding brake at red light: ~1000
Sometimes acceleration doesn't make RPM higher.
Sometimes acceleration causes RPM to rise (to around 2500), then quickly drop, then rise (to around 2500), then quickly drop, until cruise speed is reached.

Many of you suggest that 7-8 around-town driving is normal. My figure is 8.3, which is about 1 higher. Even if I accept that, is there any possible explanation of the high fuel consumption of my long-distance country driving? I know people achieving 1300KM per full tank, while my record is 650KM, which is half.

By the way, I feel acceleration at low gear not as smooth as the first few months. Is that a problem?

Is there someone in Melbourne who is professional in fuel consumption and provide car checking service?

[Eureka]

My personal record for my CRD1 5-speed manual is 1323 klms to a tank when the fuel light came on, but that was with some pretty extreme driving, and a completely full tank at the start.

Mostly, if I am trying to drive efficiently, I try not to rev past 2000. 

I have noticed a few times that if I accelerate hard, there is a cloud of stuff coming out the back of the car and I guess it is wasted fuel.

I know people achieving 1300KM per full tank...

There will be noone with an automatic getting anywhere near that.

I'm quite sure your car has no problem.

[Doggie 1]

Mine's a manual and I refuelled today.
It achieved 4.9 l/100 kms for a tank distance of 1055.1 and took 52.80 litres of diesel.
As Pip said, an auto wouldn't be doing 1300 kms, I wouldn't think.

I have noticed a few times that if I accelerate hard, there is a cloud of stuff coming out the back of the car and I guess it is wasted fuel.

I'd suspect it is not wasted fuel at all but sooty smoke. Not all the crap can be recycled and without a DPF it just blows out the back.