Fact is that the Ioniq has a low compression engine using the Atkinson cycle. Therefore high octane fuel is bare nonsense and not affecting fuel economy at all, only your wallet.

 

What he said. :laugh:

Not only that there may be lifespan costs further down the line.

This is, however a different question than one about the quality of the fuel. :nerd:

 

Ok, so coming from the world of diesel for the last decade (so please forgive my ignorance), how does one go about determining (and verifying) quality fuel?

 

Quality should be standardized if you go to those larger chain gas stations. Not sure about the average pump at tesco.

 

QUALITY is standardised to published standards to which all fuels must comply. Additives can vary

 

I believe regular gasoline in Europe, and and perhaps England as well, is 91 octane, not 87 octane like here in the U.S. Also in the U.S. cities in high elevation areas have 85 octane as well, as less octane is needed at higher altitudes which would be comparable to 87 octane.

I have tried premium gas in my 2010 Prius which uses regular gas. I noticed no difference in mpg's or performance by using premium gasoline over regular. The only thing noticed is that premium cost more per gallon than regular.

 

.... in the U.S. cities in high elevation areas have 85 octane as well, as less octane is needed at higher altitudes which would be comparable to 87 octane.

Here at Salish Sea (Puget Sound) sea level, 87 octane works the very best for my last 5-6 cars, whether using E0 (ethanol-free) or E10 (10% ethanol blend). For years I've been curious about 85 octane at higher altitudes, but haven't had recent high elevation vacations to test 85 octane gasoline. I most would like to test 85 octane E0 (all gasoline molecules are 85 octane), believing it superior to 85 octane E10. As it is, 85 octane E10 is a mixture of 10% 114 octane ethanol molecules AND 82 octane gasoline molecules (which would be spooky).

 

If the aim is to improve fuel consumption figures the use of super unleaded fuels may or may not help. The following suggestions really can help in improving matters:

Reduce the weight of the car by not carrying unnecessary stuff in the boot, and by not filling the tank up to the top. 45 litres of petrol weighs about 37kg, so by only filling the tank to say two thirds full you will be carrying about 12kg less in the car which will have an effect in the long run. To be clear I am not advocating running the car until the fuel gauge is in the red.

Plan your journeys so that you don’t have to refuel at motorway services unless absolutely necessary. Fuel quality might be good, but the higher cost will hit your pocket if not your MPG figures.

Figure out if it’s really cost-effective to go out of your way by a few miles to refuel at a garage that you know sells petrol at a penny or two cheaper, or because a particular chain offers you points. I realise that some drivers with company fuel cards might not have a choice where they refuel.

Try to keep the drag coefficient down to the manufacturers figure of 0.24 by not fitting roof racks, bike carriers and trailers. Even those little England flags that some clip to the driver and passenger doors when England make it to the World Cup finals will increase drag. However, current performance tends to indicate that the likelihood of this happening is decreasing.

Keep out of the “aggressive” area of the driving style display.

 

the only other thing regarding fuel is the "premium" brands like shell, esso, BP etc have a better additive pack so tend to keep the injectors and fuel system cleaner in better condition compared to supermarket brands which tend to have minimal additive packs

this will have a long term benefit more than fancy high octane fuels in the Ioniqs low compression Atkinson cycle engine

the base fuel for all tends to come from the same tanks at the same refinery, it is just the additive packs which are added as the tanker is filled that makes the fuel different between the brands, super market fuel is cheap for a reason, I tend to avoid using except for the odd fill up

this is why in the US the service schedule recommends as fuel system cleaner @$20 unless you use premium brand fuels

 

I know pretty much everyone has said that No, higher octane fuel doesn't help with consumption and that's 100% correct. Higher octane simply resists pre-ignition on a high compression engine better than low octane fuel does. The reason the Sonata gets a 10HP bump with higher octane is because on lower octane it detects the pre-ignition using knock sensors and retards the timing accordingly which causes a power reduction. In a car that does that, I say always use the higher octane so that it doesn't have a chance to knock. Our motors use the Atkinson cycle which really just means that it leaves the intake valve open through part of the compression stroke effectively lowering compression making high octane fuel a complete waste of money.

As far as anecdotal evidence goes, I am currently running a tank of high octane fuel in my car because they reversed the buttons on the pump and I wasn't paying close attention. So far my consumption has been unaffected.

 

I think it would also take a couple of tanks for the engine ECU to adjust to the different fuel, plus the first tank will be a mix of low / high octane fuel as the tank would not have been dry when you filled up as well

 

That's true. I don't believe the Ioniq tries to adjust the ECU for different fuel octanes though. I have no technical source for that but based on the type of car and engine, I really don't see why it would.

 

Think Dave summarised things nicely. instead of worrying about what's in the tank, concentrate on what's in the trunk.

I usually carry a large bag filled with PPE, including boots and hard hat. There's a box containing binders and company promo materials, plus a `go` bag I keep in there for unexpected stay-aways. There's a large plastic box containing the battery booster, tyre pump, emergency kit and sundry items.

None of them particularly heavy by themselves, but they totalled over 70 lbs / 31 kilos. Gotta be a couple of mpg in that.

 

If you cant miss your stuff kick one passenger out.
I' m almost continuously driving with 2 persons, a spare wheel with jack, tools, and emergency kit. Fuel consumption around 25 km/l over relative short distances. Better get that pound of lead out of your right boot instead of lurking on a high octane fuel pump.
Its a mystery to me why people always believe to have better knowledge of the cars engine requirements than the manufacturer. RTFM advice= normal unleaded fuel.
Diabetics dont feel better drinking RedBull.

 

If your engine is set up to burn 87 octane(most are), then use 87 octane, whether brand names or low-ball "generic" gas. Higher octanes won't help 87 octane designed gasoline engines to get better mpg. Saying that tho, there is a difference between 87 octane, 10% ethanol blends (E10) & 87 octane, ethanol-free(E0) gasoline. With careful records over decades of use, my last five 87 octane gasoline engines have shown an 8% to 5% increase in mpg, E0 over E10.

 

Yes the calorific content of ethanol is lower than that of pump fuel, so when it is added it does have an effect on overall consumption.

However, the thing is not to get too hung up on this. Even with E10 the difference is about 10% or about 5 miles per gallon. Unless one is embarking on a long journey it really isn't justified to drive more than about 5 miles to find a non-E10 pump. Same argument for the occasional fill-up with unbranded fuel. As we've already said in this topic, carrying unnecessary extra weight is a bigger long-term issue for mpg than simple choice of fuel.

 

Yes the calorific content of ethanol is lower than that of pump fuel, so when it is added it does have an effect on overall consumption.

The caloric content of ethanol is 3% lower than E0. Adding 10% ethanol to E0 would only lower MPG by 0.3%. The difference between E10 & E0 MPG is ~ 8% to 5%. 87 octane gasoline engines work best with 87 octane gasoline, E0. Defined 87 octane E10 is actually a combination of 114 octane ethanol molecules & 84 octane gasoline molecules, neither of which are 87 octane. It is the combination of ethanol lower caloric btus(small effect) AND the mis-matched octanes (much greater effect) that cause the total 8% to 5% MPG difference between defined 87 octane 10% ethanol blend & truthful 87 octane E0.

 

In Canada, some stations are E10 for all octane levels, but many stations only have E10 in the low 87 octane fuel and E0 for the higher 91 octane fuel.

I've read of long-term problems ethanol can cause for cars, such as fuel-line corrosion, higher water attraction, and poorer shelf-life.

So my question is would it not be better to get the E0 91 octane over the E10 87 octane?

 

yep, spot on

BUT those pesky enviromentalists prefer e10 as it is a quick easy win for CO2 reduction as the ethanol is "supposed to be from sustainable sources" and govt's see it as a quick win for their emission targets

 

Hm, those geeky Koreans must be doing something to these engines cause where I live, the regular fuel is 95 octane, while premium is 98.
Can't otherwise explain why it's not advised to use 93 octane fuel in NA and 87 instead, all the while Europe goes on 95 as standard.

 

in UK the fuel spec is 95RON which roughly equates to US 87 octane

you need to be careful to compare apples with apples

its all marketing BS, as 95 is a bigger number so must be better than 87 although they are different measure which are in fact the same (see windows, iPhone etc numbering)

 

Of course, I was only talking about engine tuning to different fuel octane, that's all
If standard in US is 83 octane, and Kappa runs fine on them, then I guess something must be adjusted for Europe to cope with 95 octane equally reliably.
I'm not an engineer, though, so have no idea what would that be. Air/fuel mixture? Some additives?

 

I'm an eco-nut and sad about ethanol. Less emission while running but I have to use more of it to go the same distance. Reading through, looks like my recent post about sudden mpg drop might be answered. I'll drive by the fuel station and see if they did switch over. I was more excited about the dollar amount!

 

Very difficult to accurately compare fuel consumption of different fuels without having consistent conditions throughout the tests, ie you need a to do it in a lab with constant ts and ps. Just because you got longer range from a thankful of one gas compared to the previous thankful of another brand is meaningless because the environmental conditions, traffic, route etc would all have to be identical to make a fair comparison, something that can never be done in practice.
I have done huge mileages in my cars using mainly supermarket fuels, 450000 in the case of my Renault on the original engine, still running well when sold, by fastidious oil/filter change intervals, never revving hard until full temperature reached, avoiding very short journeys to minimise that condensation effect on exhaust and engine oil. This saved far more money in repairs than all the hypermiling and worrying about using heavily advertised fuel brands would have done. Never had any problems whatsoever with clogging of fuel pumps, valve gear etc in the last 3 cars which between them totalled over a million miles run.
Hope I haven't jinxed this Ioniq by writing the foregoing!!

 

I do use Shell V Max, only, in my Brabus Smart, but is in a relatively high state of tune,about 16 per cent beyond factory output, and in my Sports racing car which is running 11 to1 compression.Every day cars filled up whenever I see low priced fuel and need more than 4 gallons