[Zana]

Hi,


I'm new to the forum, and recently bought an ex demo 2018 New Generation i30 DCT 1.6l diesel (Premium SE trim if that helps). One of the reasons for buying the diesel was fuel efficiency. However, in the past 2 weeks of driving the efficiency has been pretty appalling. I've quoted some figures below, averaged over a couple of journeys in each case:

Mostly town driving efficiency: 35 mpg

Mostly dual carriageway driving: 41 mpg

In all trips, we left the climate control at 21 C with the A/C off and fans set to low. The heated steering wheel and seats were off for most of all of the journeys. We know that the quoted combined mpg by Hyundai is 68.9 mpg but we haven't managed above 44.4 mpg yet.

Obviously we wouldn't expect to hit the manufacturer's quoted "best case" figures but my partner has a 2014 Seat Leon 1.6L diesel DCT which allowed us to conduct a comparison test. He did the same journey in both cars on consecutive days. The outside temperature and traffic conditions were similar, yet the results are very different:

Seal Leon: 60.2 mpg

Hyundai i30: 44.4 mpg

I don’t know what we’re doing wrong but even getting 44.4 mpg was difficult, with my partner trying to drive as efficiently as possible. Lastly, it is unlikely it was doing a DPF regen every single journey, (we did this test twice with similar results). Can anyone please shed light on why I'm having such bad fuel efficiency?

In addition, it would be helpful to try and see how the mpg changes instantly, but the meter is maxed at 50 mpg. The i30 driver’s manual does say there should be an option to change the units to L/100km (which is my preferred unit) but the car itself actually only provides two options: mpg using US gallons or UK gallons. Has anyone experienced this in the UK version of the i30 software and how to change it? Maybe when using L/100km it wouldn't be artificially maxed at 50 mpg?

[Aussie Keith]

I can't help with changing the readout, but I can tell you that it takes some time for the engine to hit its peak fuel efficiency. On my car with 40k on the odo, I've seen as low as 3.5l/100 which from a conversion website is something like this: 81 miles per gallon equals     3.5 liters per 100 kilometers - - imperial mpg apparently. I'd be amazed if that were actually true, but if I see more than 5 on the highway I'd be disappointed (about 55mpg). 

So give it some time to get into the groove, it will be worth it in the long run.

[Dazzler]

Thanks Keith,

Welcome @Zana

Sorry you haven't had much response to your query. I remember reading it late in the evening and meant to get back to it.

I'll tag helpful member @Hati who has a similar vehicle here in Australia for feedback on his milage. He had an earlier generation Diesel i30 as well.

[Hati]

Bloody hell Dazz, your memory is pretty good for a more senior citizen

Yeah, I had an FD CW crdi manual. The best it did was under 6 L/100 Km in town. I was very happy with that. I was routinely getting on or over a 1000 km to a brimmed tank. I did not baby the car, usually first off the lights and not many cars passed me.

As for the PD (DCT), the odo didn't go past 10000 yet, so not a lot to say as it has not been run in yet. The FD really started shining well after 30000. The PD computer says 6 L/100 Km since it was born, and hovering around that figure even for short trips. No pussy footing with this one either.

[Dazzler]

Bloody hell Dazz, your memory is pretty good for a more senior citizen

Yeah, I had an FD CW crdi manual. The best it did was under 6 L/100 Km in town. I was very happy with that. I was routinely getting on or over a 1000 km to a brimmed tank. I did not baby the car, usually first off the lights and not many cars passed me.

As for the PD (DCT), the odo didn't go past 10000 yet, so not a lot to say as it has not been run in yet. The FD really started shining well after 30000. The PD computer says 6 L/100 Km since it was born, and hovering around that figure even for short trips. No pussy footing with this one either.

Cheers Hati. Hopefully that will give our new member something to work with.

6 L/100 kms = Approximately 47 mpg I believe.

[xiziz]

I think the diesel takes some running in, my figures stabilised at about 20000km to a average of 4.45l/100km, up slightly the past 20k, I think because my rear brakes were in need of new pads and grease on the pins. How far has yours run to date?
Getting between 3.9-5.0 depending on driving conditions, temps, roofbox on etc. Should be the same engine (u2) in the pd too and the dct is supposed to get nearly the same as manual.

I live in the sticks though, so I drive a lot of longer distances(rarely less than 55km) without traffic/intersections at 70-90kph which helps economy a lot.

[Hati]

I live in the sticks though, so I drive a lot of longer distances(rarely less than 55km) without traffic/intersections at 70-90kph which helps economy a lot.

I recall a long time ago a science program on the idiot box that talked about vehicle efficiency and the outcome from that (IIRC) was that 90 km/h was the most efficient speed for fuel consumption. My own "tests" seem to have confirmed that. The problem for me here is that there is hardly any 90 zones. Either it's way under (built-up areas) or way over (100-110 legal) so could rarely slot into that 90 km/h "sweet zone" without becoming a mobile roadblock.

[eye30]

I live in the sticks though, so I drive a lot of longer distances(rarely less than 55km) without traffic/intersections at 70-90kph which helps economy a lot.

I recall a long time ago a science program on the idiot box that talked about vehicle efficiency and the outcome from that (IIRC) was that 90 km/h was the most efficient speed for fuel consumption. My own "tests" seem to have confirmed that. The problem for me here is that there is hardly any 90 zones. Either it's way under (built-up areas) or way over (100-110 legal) so could rarely slot into that 90 km/h "sweet zone" without becoming a mobile roadblock.

Some 50 years ago i recall that 56 mph, 90 kph, was always quoted as most fuel efficient speed.

Trouble is when i was pulled by police in 30mph zone they threw the book at me.... 

[Zana]

Thanks everyone for the replies.

After reading some other posts before posting, I'm also doing an actual physical test over the Christmas period. I filled the tank to the brim and have driven nearly 350 miles (560km) so far. Will probably go refuel in 2 days time and I can check if the software is relatively accurate.

To answer some of the questions about it needing some time to reach peak fuel efficiency, it has done just over 3500 miles so far (5600km). So I can understand it's pretty new and might not be reaching satisfactory figures yet. I'd be super impressed if my motorway journeys reached 55+ mpg. As a lot of my journeys are going to be for work where I can reclaim miles done, I'm keen to get a good fuel efficiency as possible. Fingers crossed that happens!

I'll let you know what my  filling the tank to the brim showed in case someone else reads this post and are curious. If I remember I'll repeat the test once I reach 20,000km to see if things have changed. I'm hoping that the software is accurate and I need to just drive in the car more.

I do wonder however if the engines in the Australian i30s are different to the ones shipped to the UK. Would anyone know if it is? Or anyway I could find out?

Edit: I forgot to mention changing the units. I've not been able to resolve this and have asked the dealer. I'm just confused how the instant fuel gauge is maxed at 50mpg and yet the quoted combined mpg is 68.9. So Hyundai has created software that can't even show the efficiency they've quoted. It would be handy to know if there are any UK i30 owners who have resolved this?

I have seen one post from someone living in the UK and who quoted instant figures of 60-70. However, the post was nearly 2 years old so I don't know if they're still on the forum.

[Dazzler]

@Zana

They are the same engine (basically) from the Korean factory that supplies Australian i30s as what is used in the Czech factory.

In the Series 1(FD) and Series 2 (GD) the European delivered diesels had a Diesel Particulate FIlter (DPF) whereas the Aussie cars did not. As of the Series 3 (PD) we also get a DPF now.

Member @AlanHo did some testing and found the DPF only made a small (negative) difference to the fuel economy though. (maybe one or 2 MPG I think)

If you are into enthusiastic fuel saving you might find this old thread interesting. After having a 2008 i30 Diesel and 2 Camry Hybrids (2010 and 2012) I got in the habit of driving my cars very frugally, but since I've put sportier tyres on my PD SR.. I've been less cautious. 

i30 Hypermiling Techniques

[AlanHo]

@Zana

As Dazz mentioned - when I had an i30 hatchback I carried out a number of experiments to measure actual fuel economy - this included checking the accuracy of the odometer against the Km posts on the M5 motorway over a distance of 180 miles. It was 1.8 % under reading which meant that if the car thought it had done 100 miles - it had actually travelled 101.8 miles. Not much of a difference - but as Tesco say - every little helps.



I kept the car for a year and 11700 miles during which time it averaged 55.68 mpg. I then traded it in for a 2013 i30 manual tourer which averaged 53.2 mpg.

I also did some experiments to determine the effect of the DPF regen and found, as Daz remembers, that on mixed journeys when it regenerated most often it lowered the mpg  by about 2 mpg. On a long trip to the Lake District and back the car did almost 400 miles between regens and this lowered the average by only 1.3 mpg

Your economy is so low I am tempted to think the units are set to US gallons and not imperial gallons - it might be worth you checking.

My current car - a KIA Niro hybrid with a 1.6 petrol engine has averaged 60.35 mpg over its first 15,300 miles - which is much better than the diesels.

[Dazzler]

Thanks Alan,

I was hoping you would post something like that! Perfect! 

[Zana]

@AlanHo

Thanks for reposting your findings. Do you think the new generation 2017 i30 model, and it being DCT, would have much of an effect on the fuel efficiency compared to your numbers and for yours being the 2012 model?

My car is definitely set to UK gallons, this was the first thing I checked when trying to change to it km/100lites. Although, after i refuel I might change it to US Gallons just to see if the units change - maybe there is a bug in the software. Nevertheless, on a more recent journey of approximately 100 miles, I was able to achieve averages of 46mpg and 50mpg (to and from). This was again trying to drive a frugally as possible. So a little bit better but still nowhere near the quoted figure of 68mpg, or even what you were able to achieve in your 2012 model.

I think my only options now are to firstly double check the accuracy of the software for the 2017 model by filling the car to the brim (results due tomorrow), and secondly, see whether fuel efficiency improves after 15,000 miles or so.

I have also contacted the dealer, who have yet to come back to me about the massive differences in quoted versus realistic figures.

[Dazzler]

I think the DCT should be as efficient as the manual. I think official figures for the DCT versus manual are slightly in DCT favour.

My DCT turbo petrol has been excellent for a sporty model I'm averaging 7.2 L/100 kms against an official figure of 7.5 combined. On trips I can get down to mid to low 6's. Mind you I have done nearly 45,000 kilometres in 18 months.

[Zana]

@Dazzler

Well for my first few long drive with the i30, we did 411 miles (661km) over the Christmas period and filled it up again yesterday. The fuel efficiency was 5.8 l/100km or 48mpg. The gauge on the dash was correct and read 48.1mpg (actual figure was 48.13). So it is good to know the car is accurate in estimate efficiency.

I'm surprised long trips are still so fuel inefficient and I'm finding it hard to get above an average of 50mpg, but I'll wait and see if this improves with more use of the car. Not sure I have any other choice.

[MT-RED]

I definitely think actually checking the economy based on brim to brim fill ups is the best way to go. At least this gives you a real world view of MPG and cost per mile.

 You should get a decent initial view of reality after 2 or 3 tanks but obviously the longer you measure the better in terms of averages. Personally I have always used Fuelly to track its a decent enough free App so that or something similar might be worth a look.

[MT-RED]

That does seem really low TBH. It won't make a massive difference but are you avoiding Supermarket Fuel?

[xiziz]

I don't think supermarket fuel makes that big a difference in the long run. I run only the cheapest fuel (Except once when they were out at a service station during one of my longer trips and I had to fill with premium diesel).

I will bump my table in here to, yall have to convert it into whatever non metric units you like. I got every tank recorded since start of 2017. 2016 I only recorded 2 tanks, so take those numbers with lots of salt. Total distance driven on these numbers are 84874km. So the computer should be about 2% kinder than real life to economy figures. As you see from the plot, it mostly goes hand in hand but occationally (usually on long trips) they get unsynced. Average speed is derived from actual trip times (ie, the cars counter for engine running, so idling included) and distance driven. EGR blocked november -17, and you can see an increase in actual fuel burned since then, but it really helps with the choppiness of the engine on low RPM/Load. Thinking of removing it again though, drop is about 8% efficiency.

[MT-RED]

Thanks Xiziz, thats really useful insight. I have to say I am surprised at the 8% difference you are seeing following the EGR delete. I believed it had a negative impact but thought it was usually to the tune of around 3% - you live and learn 

I agree Supermarket wont make a massive difference, or not from my experience anyway. It does (or did in my previous car at least) make enough of a difference for me to stop using it though and was cost effective. 

I measured my Passat in the UK over sustained periods between ASDA / Morrisons (Supermarket Fuel) and BP / Shell, each time sticking with the lower octane cheaper options. I regularly and reliably witnessed circa 50 mile difference per tank when avoiding the Supermarket Fuel. This was a 70L tank and therefore the gain was around 3MPG (on average) when using BP or Shell Fuel.

The Shell / BP fuel cost in at around 5 pence more per litre where I live, so it was around £3.50 more per tank to fill up. Given we pay roughly £6 per UK Gallon, it was more cost effective for me to use BP / Shell vs Supermarket thanks the marginal MPG gains I was witnessing. 

I have no idea if I will see the same out of the i30 though as I don't collect it until Wednesday - time will tell.

[xiziz]

Yeah, they add more than 5p here, more like 15p in my town. I usually fill at the autonomous station, compared to the manned station. Both belong to big oil companies though. (ingo/circle k and okq8 respectively).

EGR numbers are probably exaggerated by my driving, I only do about 5000km above 2000 rpm(100kph) cruising, which is when the EGR closes by default. So my driving is mostly done in the zone where EGR would decrease consumption, but since its blocked, it won't (but I get the positive effect more time ofc) . My commute is 75km of rural roads, low traffic and I can count the turns I have to yeld on one hand. No lights or roundabouts.

[aksel13]

I have the same car here in UK. And I am getting the similar mpg. I was disappointed as well and not sure if I would pick another hyundai next time now. Even though I liked the i30 Dct gearbox they tend to change gear very early in city ride and by using wrong gear at wrong rev it consumes a bit more on fuel.

[beerman]

The i40 with 7 speed transmission gets 5.3/100l on the highway with some drivivng through the suburbs to get there.

The i40 is a 1.7l rather than the 1.6 and is a bit heavier from memory.

Based on the 6 speed i40 I had previously a straight highway run should get to the mid 4s.

[electroman5000]

Hi!

Is your i30 fitted with AdBlue exhaust treatment system? If so, that decreases fuel economy greatly, by keeping the liquid warm (there are heating elements in the AdBlue tank). Obviously it is only operational in the cold period, so you should see better figures in the warmer time of the year. Also their DPF regeneration does kick in a bit too often (as I've read, anyway), so that might contribute.

Some tips for getting best fuel economy:
 - keep your tyres properly inflated. Go with recommended inflation (can be found in the manual), add +2 +3 psi. Might just save some extra 0.06 l/100kms
 - don't carry unneeded junk in the car with you. Less weight - less fuel used
 - when on motorway keep a steady speed. If you're not very gentle with the gas pedal, then use cruise control, or (my favourite) speed limiter. 
 - in cold times keep the climate control switched off. Allow the engine to warm get up to the operational temperature as fast as possible, and only then switch the heating on. Or at least let the temperature gauge to raise up to +60 +70, before switching the heating on.
 - (pretty obvious) read the road ahead, plan your actions and adjust speed, so you minimise the use of brakes, and accelerate as least as possible.
 - don't shift up too soon. Shifting too early puts extra strain on the engine, and doesn't really save you that much fuel, which would offset the expenses for engine repairs (if you are planning to keep the car for long time). The sweet spot (for fuel economy) for 1.6 CRDi is between 1500 rpm on a flat surface up to 2000 rpm. So if after shifting up the revs drop below 1500 - that's a bit too early.  For example: driving at 30 mph in 3rd gear at about 1900rpm is a lot easier for the engine (about the same fuel wise), rather then in 4th gear at 1300rpm. Put is simple - the faster your engine responds to a slight gas pedal press - the better. You have better control, engine is happy, your fuel economy is just as good. Of course if it's a completely flat, or a slight decline, then you can upshift, and trundle along at slightly lower revs.
Since you've got a DCT, try shifting with steering wheel mounted flaps - let the engine rev up a little bit more, than 1800rpm (that's what my i30 tells me to shift at), and see if there's any difference.

Hope any of this helps.

Keep us posted of any results or changes in your mpg figures.

Cheers!