fuel consumption

[clintondane]

hey guys i've got a 2001 legacy blitzen and recently i've had a few issues with it, knock sensor, oxygen sensor replaced and gearbox rebuilt. it ate itself through no fault of mine. anyway when i first got it i was getting about 10.5 litres per 100km but now getting about 12litres per 100km, i'm not driving any differently so i'm confused. any help appreciated.

[Guest]

i get about 13L/100km most of the time in my 99 B4. how did you get 10.5???

[Guest]

How often is it serviced? if it hasnt been done in a while try replacing all the filters just in case one is blocked. Cloged air filters can cause an increase in fuel consumption in an NA but nure of tubos.

Just a thought, hope you get it sorted

The best thing to do would be to take it into subaru to get them to check what the computer is saying, may be having to retard the ignition or something which would increase fuel consumption also (i Think).. what fuel are you using?

Jake I get about 10.5, the newer revisions are (seem to be) better on fuel.

[Guest]

My slightly increased fuel consumption might also be due in part to A- my driving, B- my driving, and C- the mines ecu.

[Guest]

Is that 12L/100km round town or open road?

If round town, that isn't too bad.

I'd definitely put a clean air filter in as that can greatly impact fuel economy and should be done pretty often anyway. I've also found in the past that my fuel consumption goes up in winter. I think it has something to do with a winter blend of additives in the fuel?

Mine is on 11.1 average over the last 15,000km. If I'm just doing round town driving (i.e. to work and back, rush hour traffic) I've seen as high as 14.8 recently. Open road runs I've seen as low as 8.9 but are generally around the 9.5-10 region.

[Guest]

 webup said:

I get 380kms from a full tank of 98Oct

in the S402? wow. that's sweet F all. must be a lot of town driving?

[Guest]

 jake_the_muss']

[quote name='webup said:

I get 380kms from a full tank of 98Oct

/quote]

in the S402? wow. that's sweet F all. must be a lot of town driving?

Id say, my 01 b4 is at 300km at half tank, im currently at 480km with just under a 6th to go.

[Guest boostin]

It can be as simple as a bad batch of fuel too.

[richm]

With my manual '01 GTB I have acheived an average of 10,003 litres per 100km. That's after 35000 km. Worst ever 12.5, best ever 8.8. Every single tank is measured. I don't drive slowly at all but do keep the car regularly serviced and like to brake easy. Also improved after I converted to parallel turbos as they share the load more evenly I guess.

But right now I'm pretty interested in "downgrading" back to an Impreza as the heavy GTB is doing my head in.

[richm]

Oh, forgot to mention:

With 98 octane fuel consumption is higher. 10,3.

With 95 it is only 9,8.

Don't ask me why.

It goes against what all others "believe" that using 98 is more efficient to use. But in MY GTB that is not the case. This based on 22000km om 95 and 13000 om 98.

Also there is no difference with or without AC on that can be measured. And open road vs city driving is only marginally different. My theory here is that I like to drive 120 on the open road and therefore use more than one "should".

[Guest swiftbrad]

interesting... hey is it true that when you go parallel that you lose the subbie rumble?

[nickmcgill]

How are you all being able to tell what the L/100km is, Is there a feature that I don't know about or counting how many ks you get roughly to a tank ?

[Bazza-NZ]

 nickmcgill said:

How are you all being able to tell what the L/100km is, Is there a feature that I don't know about or counting how many ks you get roughly to a tank ?

resetting the trip meter for every full tank of gas and then you just work it out from that... use how many liters you put in the car (check pump before you leave the station) and use the finally figure from the trip meter when you go and refill

[Guest keltik]

Yeah trip meter and the knowledge that once the empty light comes on ive got about 6liters left in the tank. Gets me a pretty accurate MPG figure to go off. I get around 8.2L/100km open road driving and maybe as low as 11L/100km if im doing a lot of town driving.

But i dont have no dirty turbos!

[Guest]

 keltik said:

But i dont have no dirty turbos!

no BOOST either!

[nickmcgill]

Haha ^^

Yeah I normally do that anyway to give me a rough idea on how much fuel I should have left, My empty light doesn't work sadly must get around to fixing that one day lol.

Open road I normally get about 600k to a tank of about 45L.

[richm]

Off topic but replying to swiftbrad. Yes you "loose" the subie rumble to some degree. It sounds like an Evo instead. Perhaps one could say it sounds more "refined". Comes down to individual preference at the end of the day.

As for methods of measuring, one can set the trip meter to 0 for ever fill up and then simply record the number of kms travelled vs litres purchased (from receipt). This of course assumes your speedo is correct which in my case has an error of 1% when the tread on the tyres is between 4 to 7mm.

[clintondane]

mixture of town and open road driving running on bp 98. admittedly it's time for a good service but crazy how it suddenly got really bad. i know when the oxygen sensor shat itself the fuel consumption was terrible. will take it in to subaru at some time in the near future and see what they say. best figures recently were 11.6 which i guess is better but still worse than it was a while ago. thanks for the suggestions though guys.

[GravelBen]

 richm said:

Oh, forgot to mention:

With 98 octane fuel consumption is higher. 10,3.

With 95 it is only 9,8.

Don't ask me why.

It goes against what all others "believe" that using 98 is more efficient to use. But in MY GTB that is not the case. This based on 22000km om 95 and 13000 om 98.

Interesting, I find the opposite with mine ('02 GTB E-tune, manual) - around 10% thirstier on 95 than 98.

I usually average 9.5-10.5 L/100km in mixed use (cold starts, short trip rounds town, gravel thrashings, longer trips), best I've seen over a tank was 8.7 from memory. Did a roadtrip from Cromwell-Taupo and back in January, final average for that was 9.2 over the 2686km and we weren't being grannies about it.

[richm]

Yeah, I think it is strange too, but as I wrote earlier: don't ask me why. We both have the same cars with the same average approximate consumption but definitely have the opposite experience when comparing 95 to 98. Even stranger I used to be a loyal Shell customer but when they changed to V-power consumption went up 5-10%. After 10 tanks of higher consumption and frustrated questions to Shell, I really had no choice and was forced to go to Caltex for 95 and BP for 98. I did actually ask Subaru about it but they didn't have anything concrete. Any theories? Does anyone else notice this with Shell v-power?

[Guest keltik]

Different shut off points with the pump nozzles? Different ways of figuring out your k per l? Different additives in the fuel?

Could be a heap of things. Personally my mpg usually has about a 10% margin of error due to shitty maths and different driving styles.

[pharnos]

I fill right up - even topping it up after the pump stops itself. The car is a 97 TS-R auto, so this isn't gonna to be that interesting to most of ya, but I thought I'd post it up anyway...

ahh, here's a link to the image so you can read it properly

http://pharnos.orconhosting.net.nz/legacy/fuel_economy_97_auto_tsr_legacy.JPG

[dubbedup]

looking at that ^^^^, can you change it to go in octane rating and then k's per tank..... good to see a 15c/k up there. ;D

[pharnos]

did an order on kms per tank (assuming a 60L tank size) with the type of fuel next to each - don't forget many of the high kms per tank results will be long distance open road trips.

[Max Headroom]

 pharnos said:

I fill right up - even topping it up after the pump stops itself. The car is a 97 TS-R auto, so this isn't gonna to be that interesting to most of ya, but I thought I'd post it up anyway...

I'm glad you posted that chart. I previously got 28mpg out of my BF7 2.2l n/a wagon quite consistently, and I'm currently getting 23mpg out of my (new to me) BF5 GT 2l single turbo. I felt that the GT should be capable of better economy considering it's typical use is 80/20 open road/city. Maybe it's not so bad after all!

It's getting a thorough service at the moment, so perhaps things will improve further when I get it back.