[PRH79]

So, I've had my i30 CRDI Active Blue Drive for 13 days, done 1400 miles in it, and will be filling up again later.  Last fill up approx 400 miles ago netted me 70.71mpg over 590 miles. The first 400 miles or so from new was 59.3mpg. According to the car's avg mpg reading, which I reset when I last filled up, I can't expect much more than 60 this time - but the driving has been much more stop start than the good long motorway runs I had last time out.  Is anyone regularly getting much more than 70?  I do a lot of motorway miles, and was hoping to be closer to the 80 mpg extra-urban that Hyundai's published numbers say - I know getting that may be unrealistic if anything at all happens (I have a heavy breakfast, I drive into a light headwind, the road is even marginally up hill etc) but I was expecting to be closer.  Of course, I have also been told the engine should 'loosen up' a bit with some miles on it, so maybe it will get better.  This isn't to say I'm not happy - my previous car got 50mpg on a very good run, so 70+ is great.

[AlanHo]

I would suggest that you carefully fill the car to the brim - and I mean brim it until the fuel is static and visible in the filler neck - then note the odometer reading.

Now use the car until the fuel gauge reads only 1 bar - or the warning light comes on - and brim it again until the fuel is static and visible in the filler neck - then note the odometer reading.

You will find that it takes several minutes to brim the tank fully because diesel foams so much and gives the illusion that the tank is full when it isn't. The amount it foams depends on the additives in the fuel, the flow rate, cavitation in the dispensing pump and the temperature. When I run my car until the warning light comes on, the pump will first trip after between 42 and 48 litres are added. I wait about 30 seconds and it will take another 3 litres until it trips. I wait another 30 seconds and it will take another 2 litres, a further 30seconds and another litre will go in - and so on - until eventually I squeeze 56 litres or more into a tank rated at 53 litres.

Calculate the distance travelled by subtracting the first odometer reading from the second

Calculate the amount of fuel used by dividing the number of litres added by 4.546 to give gallons.

Now divide the distance travelled by the gallons used and it will give you the true mpg for the last fill. If your new i30 is anything like mine, the result will differ from the trip computer display.

The best I have done on a tank with my car - a mixture of 80% motorway and 20% town is 57.75 mpg (744 miles travelled. 58.59 litres added)


It will be interesting to hear the result when you do a careful manual calculation as described.

[asathorny]

Your enthusiasm for you new car is commendable PRH79....

However, I stronly urge you to read/listen to Alanho's observations as he has spent a great deal of time working out his calculations.   If he suggested that I recheck my numbers I would be seriously rechecking...

Don't misunderstand we all love enthusiasm   

[Dazzler]

Welcome PRH79 are you pleased with blue drive in other ways too?

I don't think a large breakfast will have much bearing on the economy  but the other factors would explain the variance .. the rated economy is really only for comparing cars during purchase and generally are not achievable on a daily basis..

Some of our Aussie members who live and drive in very flat terrain managed to equal or better the rated figures sometimes in their series 1 (FD) Diesels 

[ajmount88]

Hi guys,

Just thought I'd try to help clear up why you are very unlikely to ever achieve the manufacturers claimed fuel economy figures in any car (at least not one in Europe). The figures are obtained by placing a car on a rolling road in a controlled environment, after first letting it acclimatise to the ambient temperature. The driver of the vehicle will ensure that the vehicle speed follows a set pattern. This pattern is called a driving cycle, and the driving cycle used in Europe is the NEDC (New European Driving Cycle). Aerodynamic drag etc are simulated on the rig by adding resistance that scales with speed. This process will never accurately simulate real world driving, as there are many other factors that affect the fuel economy of the vehicle, such as wind conditions and road surfaces/gradients. The main failings of most driving cycles, however, is the fact that they do not reflect the driving styles of the average driver. Most drivers will accelerate much more aggressively than required by the cycle, using a lot more fuel than in the testing. Secondly, many car manufacturers will program the vehicles in such a way that if they detect that they are being driven in a way similar to the test cycle, they will activate a "cycle beating" mode, which aims to maximise efficiency, while minimising emissions, at the expense of performance.

All this adds up to a lot of disgruntled drivers when they cannot achieve the quoted figures, but until the time when a realistic cycle is introduced in Europe, this will always be the case. The i30 is however a great car, that does deliver great economy in the real world, even if it does not achieve what Hyundai claim.

[Phil №❶]

There has been much written on the subject of these useless figures placed on vehicles which maufacturers are legally required to show. It's about time that, in addition on the windscreen, a sticker placed by Hyundai themselves stating the actual fuel consumption each model achieves under actual traffic conditions. Yes there will be variables, but how many of us would say that Alan's MPG figures don't represent something close to what the rest of us achieve.

If Alan quotes xx.x mpg city and xx.x mpg motorway, that would be good enough for me and a lot more trustworthy that the unrealistic scenario figures currently used.

It would IMO be much better psychology to have customers equal or exceed the economy figures, than to be constantly disappointed by feeling they've been conned.

And just for the record Alan,

What are the official Alan Ho sticker MPG's for City & Motorway?

I can consistently achieve as good or better than the stickered value (4.7l/100km) as do others here.

I put the emphasis on "I" here as the driver is probably the greatest variable. I prefer to think in terms of what the driver can do and not the car.

To complain that this or that car does not achieve the mileage expected is quite frankly unrealistic and is like complaining that you cannot run a 4 minute mile when others can.

The tests to determine the comparison figures are just that, a consistent set of tests for comparison purposes. The fact that some people get similar figures in actual driving suggests to me that they are more realistic than some think, even if they are artificial of necessity.

If you and your car cannot achieve a good mileage, look to yourself and the driving conditions imposed or chosen. Instead of dumping on the manufacturer or the tests themselves to express your disapointment why not look harder into why you are failing?

The Hypermiling thread has lots of discussion. Achieving extreme economy is a skill that must be learned and practised.

Good luck.

[AlanHo]

I do not disagree with what pip has said - an exceptionally skilled driver using hypermiling techniques in appropriate conditions can achieve economy figures close to the government figures. Such people take a keen interest in driving with a constant eye on economy - it is their passion. They are aware that every time they apply the brakes - they have wasted some fuel because they failed to anticipate the need to slow down earlier. They will choose routes that offer the best economy - rather than the shortest one that might be more hilly or prone to stop-start traffic. They will not leave unecessary stuff in the boot which adds weight, they will not leave the car idling for long periods, they will not accelerate quickly or drive at excessive speed and will always be in the best gear for economy.  They will probably have tyre pressures higher than recommended to reduce rolling resistance, will not drive through standing water if there is a dry line. Some go as far as installing sump heaters so that the engine is hot before they leave home. There are probably many other techniques to save fuel I am unaware of.

This requires a degree of dedication that I - and most other motorists - do not possess. Most of the population will sacrifice economy on the altar of just driving the car in what we would call a normal way. We use the car as a tool to get us from A to B safely, comfortably, quickly and without any extra stress.

This is not a criticism of those who take a keen interest in driving for economy - each to his own. But I think those that achieve outstanding economy figures recognise that they are in the minority.

This is why government figures are misleading - they clearly do not apply to the majority of drivers who drive modestly but without a constant eye on absolute economy. We all know that if we drive fast, accelerate harshly, drive in hilly terrain, carry extra weight etc. we will use more fuel - but what we all want to know is what economy we can expect if we drive our cars like most people do.

It would IMO be much better psychology to have customers equal or exceed the economy figures, than to be constantly disappointed by feeling they've been conned.

And just for the record Alan,

What are the official Alan Ho sticker MPG's for City & Motorway?

I cannot offer figures for just motorway driving or just city because I monitor my economy manually for each tank of fuel - brim to brim. Each calculated period will include town and motorway driving of variable amounts. I have found that the odometer reads slow for which I have to compensate in the calculation and the trip computer is not to be trusted. The instant trip on the new car is useless as I have reported before because it is an unmarked bar graph limited to a maximum reading of 50 mpg (5.7 l/100 km). I keep a spreadsheet where I have recorded every fill since I took delivery of my new car on 6th April. here it is



However - you have aroused my curiosity. The next time I do a long motorway run I will zero the average trip recorder as I join the motorway and make a note of the average economy as I exit. I will do the same for some town driving and for some B road rural trips.

Watch this space.

[Phil №❶]

@pip

I actually agree with you, I may have clumsily described the situation, but I would simply like to see a figure that was obtained in real life driving so that owners are aware of what to realistically expect. You have consistently reported exceptional figures and I applaud your driving technique. You have obviously learnt many valuable lessons during your driving experience.

@Alan

Can't wait & well expressed,,,,, as usual 

[Just Rick]

PRH79
   Last year when we got our second I30 SLX 6 spd manual we did 15000 Kilometres in the first seven weeks,over many different weather and road conditions,all the manifacturers figures of here are average combined fuel usage is 4.7 ltrs per 100 kilometres,over our trip we had fogures as bad as 6.1 ltrs a 100K's and as good as 2.8 ltrs a 100k's,since we been home and I am running a regular trips to and from work,250ks a day I'm regularly getting 20 kilometres  per ltr and thats not flat running,it's all uphill and down dale,when you have been used to a car that normally used 14 ltrs per 100K's 3 to 5 ltrs a 100K's is brilliant.
Across the Nullabor here in Oz we averaged 5.5 ltrs a 100K's sitting on an average of 130kph,if you molly coddle your car you always get good averages.
Rick

[eye30]

I would suggest that you carefully fill the car to the brim - and I mean brim it until the fuel is static and visible in the filler neck - then note the odometer reading.

Now use the car until the fuel gauge reads only 1 bar - or the warning light comes on - and brim it again until the fuel is static and visible in the filler neck - then note the odometer reading.

What I've done as I don't want to put 50 plus litres in the car is when the red light comes on note the ode reading.

Put in say 20 litres and then when the red light comes on again note the ode reading.

Doing this over several fills has given me an overall average of 38.5 mpg for mainly shorts trips, urban and the odd motorway trip. (petrol).

[Dazzler]

Just to throw a curved ball into the conversation, I do believe there are variances between individual cars of the same model and brand. I have nothing concrete to base this on just a gut feeling after nearly 38 years of driving (and over 30 cars - if I include a handful of work vehicles)

I generally drive for economy using most of the considerations that Alan mentioned (although I only slightly elevate my tyre pressures as I like a comfortable ride) No matter how I tried I couldn't get the Trip Computer average on our 2008 CRDi to stay below 5.4 LPH for any length of time...

I tended to blame Tasmania hilly terrain, but where there is an up there is a down so I do wonder if some other i30 CRDi's of the same vintage had finer tolerances.. 

..so I do wonder if some other i30 CRDi's of the same vintage had finer tolerances.. 

And herein lies the implied difference between "my car and yours". You get a good mileage and I don't so your car is better than mine. This of course might actually be true; it might depend on how it was run-in, assuming that matters. Lakes might have an opinion on that.

The point I'm making is that there are far too many variables involved for any manufacturer to attempt to offer "real world" expectations without removing as many of those variables as possible.

This is where the standardised tests come in... as much as we would like them to indicate what each of us will get, they cannot. The best they can do is offer a benchmark from which we will all get similar, better or worse results. As I said before, how you choose or are forced to drive will determine for the greatest part whether you do better or worse.

[baroudeur]

I would suggest that you carefully fill the car to the brim - and I mean brim it until the fuel is static and visible in the filler neck - then note the odometer reading.

The best I have done on a tank with my car - a mixture of 80% motorway and 20% town is 57.75 mpg (744 miles travelled. 58.59 litres added)

I'll go along with method and results.  I did get 59.4mpg over 250 miles all high speed motorway through Germany ), Holland and Belgium including a 100 mph sprint (GPS based) and usually return around 55 mpg overall.
Interestingly my new Garmin sat nav has an "Eco" option.  This gives results for acceleration and braking as well as mpg .  I get  green 80(%?) for braking but only orange 70(%) for acceleration which despite unknown parameters I would agree sums up my  non-motorway driving.  The Garmin mpg also gets very close to my top up to top up results.

[AlanHo]

We visited friends in Worcester today which entails a trip on the M42 and M5 motorways of roughly 24 miles. The distance from my house to the motorway is 4.1 miles so the engine was quite warm when I reached the motorway.

The weather was sunny and dry with an air temperature of 23*C. After accelerating down the motorway ramp to 60 mph I zeroed the trip economy and distance recorders. The intial trip economy recording - after travelling about one mile - was 56.7 mpg but it then started to steadily fall despite how carefully I used the throttle until after about 3 miles it bottomed out at 43.6 mpg and hovered between there and 46.1 mpg for about 18 minutes. It then climbed again - reaching 51.8 mpg when I left the motorway with the trip distance recorder showing 24.7 miles covered at an average speed of 61 mph.

Sods law had hit me - the damned DPF had decided to regenerate at the very time I was intending to test motorway cruise economy.

On the journey back home I repeated the test and the trip recorder registered 24.8 miles travelled, an average economy of 65.9 mpg and average speed of 58.8 mph.

There was evidence that the trip economy was still slowly climbing when I left the motorway so I expect a better result on a longer run (if the DPF lets me). I assume it took a while for the engine to reach optimum temperature which depressed the overall result.

I guess that the DPF on my car regenerates a minimum of 2 times for each fill - hence at least 40 miles are done with economy dragged down to less than 45 mpg. With this handicap us Europeans stand no chance of competing with you Aussies.

The government economy tests are carried out with the DPF in pristine condition - hence the figures do not take into account regeneration.
 

[Phil №❶]

That was probably a good thing Alan, at least we know what sort of MPG impact a regeneration has and it IS part of the normal driving function. You got 1 set of figures with & 1 set without, so I guess you take your second figure & apply that to the distance, less 2 regenerations + 2 regeneration MPG's & that would be the result for 1 tank of juice. It will never be precise coz we don't even know whether the DPF regenerates over a pre set time / distance or whether it senses a return to normal airflow, (which I suspect it does), & that would vary. It's about getting a rough realistic figure. Now all you have to do is recreate the test with DPF / No DPF in city driving, good luck with that ! 

[PRH79]

Quite a good debate here, and fascinating for an uninitiated forum user.  I will take Alan's advice re: brimming the car to get as accurate a calc as possible, and see where I go from there.  I don't want this to appear as if I am in any way unhappy with the car - I am not, but doing around 35k miles a year, eekng out a few more mpg means quite a bit more money in the bank over a period of time. 

[Dazzler]

I like to keep my overheads down and driving an economical car sure helps. After having an i30 CRDi for 28 months and a our Hybrid for 24 months I am committed to driving with a light foot and good anticipation (mostly) 

[PRH79]

Ok - I have taken Alan's advice about really filling up the tank. Got 52.5 litres in the other day while still showing two bars on the fuel gauge. Recorded mpg for that fill up was less than 50, so clearly got more in than before.  Good couple of hundred miles yesterday from Hatfield to Nottingham and back, Cambridge today, Peterborough tomorrow and Lincoln on Friday means this will be a heavy week but should get a good feel for what the car is really achieving.  Going to Nottingham the car's avg MPG display got up to 79.4, which I was pretty happy with. I realised driving home that going there must be generally slightly downhill, because by the time I got home it was 73.2 doing approx same speed.  Either way, it bodes well....