apparently the computer on our computers are "learning" ones, so best to stick with one grade of fuel.

apparently 95 ron is the way to go for the GXE.

in reality though, i really dont think it makes much of a differnece, i usually go with 95 ron at shell or caltex. recently i have gone bp ultimax of 98 ron and notice very marginal improvements (maybe its all in my head though)

I've tried all three RON from Caltex but did not seem to find any different for rev up to 6000rpm as that's the most I went. I made very sure that each tank was filled up without much mix of the other, ie at least 67 litres of each RON was filled at a time. The feeling of 91RON seems to be more smoother & softer on the accelerator Try to tell the difference yourself by asking someone to randomly fill up one type of the RON next time, so don't try to guess it if you can not tell the difference

I've tried regular as well as Optimax / 8000 / Ultimate and haven't noticed any difference. What I did notice was fuel economy improved markedly when revs are between 3000-4000 instead of 2500-3500 during normal driving.

Drive above 3000?! Sweet, that's all the excuse I need.. 5th gear on the open road... 6th and I'll have to go 130-140 to be economic? Gunna love explaining that to the enforcers...

I believe it's more to do with the throttle position, light throttle on these un-torquey engines at a slightly higher rpm would be more fuel efficient than heavier throttle at a lower rpm.

Wah, Sendog: is ur theory is true, then I m gonna try on my next tank and see if it improves fuel economy... good piece of info!! thanks.. 3000~ 4000rpm!!

Well, don't quote me on it, could just be me

Try it out, light on the throttle, just hold it a bit longer, so that u don't have to go heavier on the throttle at a higher gear.

Any car doesn't matter what engine running above 3000rpm will take up more petrol. The best fuel efficient is between 2000 & 3000rpm. For instant, if you can sacrafice the speed by driving between 80 & 90km/h instead of 110km/h or more on motorway, you will save at least one litre per 100km

I partially disagree with you there ... It also depends on how the engine is being loaded at the time. What I was talking about above, was for example you were under acceleration and wanted to get from x speed to y speed in a certain period of time. To do so close towards the car's powerband would require less throttle, but to do so at a lower rpm in a higher gear, would need more throttle. This is especially true uphills.

As I understand it, more throttle = more air, more air = more fuel. If you have an S-AFC you can check your airflow meter readings to confirm this.

If I get you right, you're talking about fuel efficient on acceleration from x speed to y speed in a certain period of time by controlling the throttle. If that's a short period in getting to, say 100km/h on high rpm will not be as fuel efficient as soft acceleration with a bit longer time to get up to 100km/h. It's easier to prove that with constant speed as I've mentioned above

Yeah I get what you're saying, but even to maintain a constant speed, I believe sitting at about 3000-3500rpm is better, as it requires less throttle, than more throttle at 2000rpm to maintain the same speed.

Could just be my car is weird, but I've definitely noticed better fuel economy :/

sendog i think i know where you are coming from
obviously cruising at 50 km/h in 6th gear will be inefficient and so on
i also try to keep a "light" throttle on

I use BP Unleaded and have managed to get around the 10km/L mark.
Company card so easy to obtain the data. See below


Odometer Litres 74872 Litres
75349 51.33 477 10.76
75594 26.24 245 10.71
76043 46.48 449 10.35
76541 7.36 498 1.48
76650 46.05 109 42.25
77054 42.49 404 10.52
77492 44 438 10.05
77877 42.29 385 10.98
78291 42.32 414 10.22

Overall KM 3419
Overall Ltr 348.56

10.1947938

My RS200 around akl city usually did bout 450km to the tank or 8.6km/L and 650km on straight trip (open road).

But to be honest I now get 13.5km/L around Akl city and that on 91Ron.
(figure that one out)

i've been getting about 410Km with $50 of 95

thats about 35L of fuel? that gives me 11.7km/L

I consider that not bad! Since I have an N1 type muffler and a HKS pod filter!

6 speed RS200 by the way

OMG how do u ppl do it?? i get approx 350km with $80 on BP 98 in my is300

Earlier discussion on similar topic - here.

I've run both 96 and 98 octane, but last time I analysed the data there was no statistically significant difference in economy between the two.

And my graphs again:

Attached Image

Here is my fuel economy, mine is a 1998 5AT
I have been using 91 always except for an economy test I did open road driving around the North Island. I used 98 and got 11.93 km/l (8.38 L/100km) and on 91 got 11.75 (8.51 L/100km).
95% of my other driving is in heavy traffic from North Shore to Greenlane and back, the low fuel consumption patches are from open road driving.



DATA
Date L/100km km/L
16/12/2005 10.56 9.47
22/12/2005 11.24 8.90
31/12/2005 10.54 9.49
4/01/2006 9.82 10.18
7/01/2006 8.45 11.83
8/01/2006 8.38 11.93
19/01/2006 10.42 9.60
30/01/2006 11.12 8.99
12/02/2006 10.28 9.73
23/02/2006 11.19 8.94
1/03/2006 10.06 9.94
11/03/2006 11.18 8.94
25/03/2006 11.03 9.07
6/04/2006 11.21 8.92
14/04/2006 10.59 9.44
17/04/2006 8.51 11.75
19/04/2006 8.50 11.76

Just a note for any RS200/3SGE owners who may have decided to run 91 after reading my post.
Since experiencing occasional engine knocking (pinging), I have changed to higher octanes 95+, which don't cause knocking. I suspect because the 3SGE engines are running such high compression, even the knock sensor cannot compensate for the NZ low octane 91 fuel.

(Sorry, didn't see this thread until after answering the IS300 one).
IS200 slushbox sports luxury: Best case 8.75L/100km (calculated). Worst case 11L/100km (estimate).

Difference in fuel consumption between standard unleaded and 98 is about 6%, with 10% extra cost is not economical. (Power also went down from 83rwkw to 78rwkw with different fuel but this may not be absolutely correct as other people lost power with no changes between the two runs 5 months apart). I haven't tried the 100ron stuff yet.

In normal city driving it comfortably gives me 600km per tank (IE I don't get nervous until I'm on about 650km - needle well below empty). The most that's ever gone in the tank was 69.7L. If you're really low a sharp acceleration will result in fuel starvation giving you warning (don't try it on a turbo engine under high boost smile.gif).

Fuel light, from memory, comes on with about 10L left. The only real way to tell how much fuel is left is to fill up as soon as the light comes on a see how much goes in. These tanks don't have a separate fuel light swith - the light comes off the sender itself, so it's possible the threshold will not always be the same. The cluster also smooths out the sender signal - it uses the speedo signal to work out when the car accelerates and disregards the sender reading until the vehicle speed stabilises.

Mos.

Next time you're doing 60km/h use 6th gear, floor it - you can feel the injectors reaching maximum load and the motor noticably labours to gear the revs higher but she don't go. oh and watch you're instant fuel consumption cruise to 30L+/100km

in my 6spd 1gfe i get 10L/100km at best. After a few big runs and a few luff days i've managed 13L/100km at absolute worst. Keeping in mind the 1g motor runs lean from the factory 10L/100km is pretty danm good consumption so it really isn't something to worry about. i used to see 20-25L/100km in my v6 ecotec commodore so coming from that we're not doing too bad!

really nice topic
bit of confused what should I go for my AS200
any suggestion?hehe~

What do you mean what should you go for? In terms of fuel?
In general better (ie more expensive) fuel gives better fuel economy, but it's not always more financially economical. You will probably need to work out the exact numbers for your driving style yourself by trialing fuels.

Black: if you got 25 in a commondore that's ridiculous!! (Or it's your driving ) The cressida averaged 22L/100km when towing a 2.2 Ton trailer - I'm pretty sure the commondore is not 2.8T (And that was with overtaking too

Mos.

i have graphs! you wanna see graphs? lol

my brother drives the car now (gently) and does about 20L/100km. Ive spoken to quite a few VX V6 owners who get exactly the same figures as i used to, they can't believe it either. It seems if you do 95% city driving you will PAY! 280km to 65L LOL

Although its not a 2.8T its 3.6L of buick goodness

And what is 2.8L? A stroked 1j? Or is the stock motor 2.8? Or is that a 7m?

My RS200 tiptronic will do 500km to a tank if i drive like an old man....

RS200 tank ( 60lt) is smaller than an IS200 though so i think it's ok...

No option here in Ireland, it's 95 ron or nothing........... seems to drive fine, was told i should use octane boosters to bring it up as these cars were tuned for japanese 100 ron ....... didn't bother as they ain't cheap!