I've never got more than 20 mpg. It may be down to my "young" driving style.

edit: A downpipe like an induction kit shouldn't change the economy bit to begin with. But yeah you will use up more fuel when you hammer it as you won't even realise you're doing it. All it does is lean the fuelling slightly and on paper "should" be fractionally more economical but negligable.

[Edited by Katana - 12/5/2002 11:31:34 PM]

 

OK, I know it's a bit of a taboo subject, but when my car was standard (excpet STI backbox and STI centre) and I wanted to get some decent economy (i.e. drive to/from work), I could easily get 360+ miles out of a tank. Personal record was just a tad over 390 on a long motorway run before I wimped out and filled her up.

Then my O2 sensor failed and I had to replace the downpipe at the same time (long story). Now I'm lucky to get 300, which to me is a big drop especially when I'm driving Miss Daisy. If I boot it, then it doesn't seem to drop a whole lot more.

So, what exactly will affect the amount of fuel used? Could something be wrong with my car and it's running too rich off and on boost?

Going from 30mpg to 22mpg by just changing the downpipe doesn't sound right somehow

Stefan

 

Never had more than 260 miles from a tank in mine. MY00 just ITG panel filter and scorpion back box, run on optimax and that wasn't thrashin it.

 

Hmm, maybe it was running too lean before

I've spoken to folk before about average mpg's and some are just sacry. It's been bugging me for a while, then I saw John Banks mention getting 300 with all his mods so thought I'd better ask.

Somethings changed for the worse (well as economy goes) and I'd like to get to the bottom of it before I start getting the bus to work

Stefan

 

Had 340 miles out of a tank of optimax today a bit of everything driving (some town, some stuck in long sloooooooooow moving traffic queue and some nice open roads and the odd sprint )
Have to say that no my car isnt running lean (i cleaned it last week inc the exhaust pipe which is now very sooty again )
Have to say that i run a PPP'd MY00 with scoobymania d/p and 260+bhp so as i seem to always get good MPG (even with high MPH ) its down to the modifications (and the PPP chip )

Tony

 

Got 330 on my tank this week Ozzy. Usually I get about 190 on a tank and I was fed up with filling up so often. So I decided to drive sensibly this week rather than thrashing it wherever possible. I drove only using a few PSI maximum boost (part throttle) and cruising at 80mph, for the other half of the trip on a twistyish A road I booted it in 3rd gear to pass wherever possible (maybe five or six full bore overtakes on the way to work). Also tried to conserve momentum and enjoy driving at the same speed around corners that I do on straights (for once ). Quite a pleasant way to drive really. When you are in the mood.

Tonight I thrashed it again and you could almost see the fuel gauge moving

If your lambda sensor is working then it is probably your driving deteriorating in the economy stakes

 

I got better mpg when I dumped the cats.put the centre cat back in recently while waiting to swap my straight through centre for a silenced one and started using more fuel again.

 

Screw economy! I keep getting mini explosions in my exhaust everytime I lift the peddle. Is this normal.

 

Hmm, looks like I'll need to do some experimenting.

Thanks Katana, as helpful as ever I'll sod fuel economy when it becomes tax free and I stop doing 12,000 miles of mundabe to/from work motorway driving.

Looks like I should start taking the bike to work and use the Scoob at nights/evenings and just give it a good thrash then

Stefan

 

Thats the spirit ozzy! Remember, scoobies were never meant to be econobox's like Mondeos and escorts.

 

I know m8, but it still needs to be my everyday car. Good thing with Scoobies is it is capable of both. Nice 30mpg when you need it and 9mpg when you're driving like a crazy loon

Stefan

 

I agree with T-UK, decatting improved my economy! The turbo spools up easier so you have to learn to be more careful with your right foot to stop it spinning up.

 

In-order to get 300miles what do you do ....get towed .!!?

I've got MY93wrx and my best is 345Km (215m) on a full tank. And that was letting tractors past ... most of my driving is dual carriageway/ motorway ...and i do tend to keep it around the speed limits when im on a run

When i open it up sure , i expect the economy to collapse ...hey , thats what we got them for ......but like a previous comment, its also my back/ to to work car.

Decat....will this help? Car is standard at moment, just put baileys on, but that hasnt made any change, and i use Optimax.

Frank

 

The car is a standard RB5 (so MY99 UK).

Doesn't the WRX and STI's all run higher boost than a std UK car? If so, then that will reduce your milage.

I just drive the car like an NA car; so below 3,000 revs. Don't see any point in using 6,000 revs when your sitting in 50mph traffic for my 30min journey to/from work.

So, can anyone suggest what technical problems would result in poorer fuel economy (whether it's 400 miles or 100 miles out of a tank)?

Stefan

 

On my my93wrx, ive got an sti backbox ...like it better than the original 2 port job, having read the comments above, ive just priced a decat centre section...

Thinking of asking father xmas for one, what do i tell him to convince him its worthwhile...in terms of economy, noise or anything else he should know?

thanks

Frank

 

WRX has also got a smaller tank!

I'd say as long as when driving 'normally' (motorway cruisin', some traffic, the odd bit of nutter speed on overtaking ) 280 on a tank would be about right. Down to 220 when lots of short journeys mixed in with traffic & more nutter type stuff; serious long & dull motorway journey at 70-75ish up to 340.
That's my differences, anyway - fairly huge range !

 

Just had 28mpg on my last tank, which included a rolling road session this afternoon getting the Tek fitted MY02, full APS system with sports cat downpipe, up-pipe, ported headers.

The 100 miles ish since the TEK have I'm sure been somewhat less economical, but that's down to enjoying the extra power.

 

Don't forget it just got colder....a LOT colder! This means MAF will see higher air density and fuel mapping will be richer to allow for this, car will be faster, more petrol will be used.

I honestly doubt this would be particularly noticable, but what the heck!

 

Yeah, it's has got colder but only just recently. I started noticing it around the time my O2 sensor failed and the DP was fitted which were both back in August.

I was still wearing T-Shirts outside until last week

If something has failed, what would have a direct affect on economy? O2 sesnory, MAF, ...... ?

Stefan

 

I only drive two miles to work,on country roads,takes me 3mins in MY01 WRX. Wish i could get 200 out of a tank!!

 

Stewie, get a mountain bike m8 or walk ya lazy bugger The cars not even warm in 3 minutes, no wonder you don't get 200-miles to a tank.

I wish I only lived 2-miles from work, all my problems would be solved

Stefan

 

just managing about 21mpg driving like a ***** but all short journeys 7miles and under so lot of cold start enrichment i guess.
scared to use boost in case i run out of petrol used to get about 25mpg but was running very lean.another scooby bonus crap mpg..ps my99/00

 

i am managing to get about 160 miles out a tank. my car is a my99 running tek3, and decat. seem to get this millage no matter what way i drive the car and as for mpg improving with the cats of, not on this car.

john do you thing the mpg is bad at the mo because the ecu is needing mapped as the cats are now of the car?
let me no your thoughts.
cheers

 

Sounds to me like your leting her boost up too easy - decat makes it harder to drive off-boost. The boost gauge performs almost like an MPG gauge IMO. Once it steps over 0psi/bar then your mpg is in trouble.

 

mine has tek3 as well wld also be lucky to get 220 out of a tank top to bottom

 

Iain if you are driving it off boost for the whole tank and you only get 160 miles then we need to check your lambda sensor - as I say I get double that - if I thrash it really hard (350 BHP wherever possible ) I would still get 160 on a tank easily... I am waiting on your word for when to map it... have you tried that MAF wiring loom yet?