munna

the reason i ask is this..

last week dropped off the mrs and little brat..hot run down the Mway, joined the A65..two largish cases, 2 adults, one brat..a laptop and my weekend bag..

car was running on fumes, so in went £35 worth of optimax.purchased at 117.9pence per litre..at 4pm, sunday..70mph, ocasionaly going to 80 for overtaking..onto the A65 again normal driving..nothing mad..just casual as you do with a fully laden car driving..

fuel when destination reached, a little bit above empty..!

fast forward to collection date..yesterday..picked them up..same people, same load..except a couple of bags of shopping!..car on fumes after the 'HOT' run down..again..£35 worth of tesco 99 this time (local shell was miles away..!)..purchased at 116.9 pence per litre..same driving style..except i cranked the boost to the 3rd setting on the FC commander..drove with my wing mirrors tucked in..(just a test)..and got home with a little bit over a quarter tank..!

surely not because of the 1pence differernce in fuel price, wing mirrors tucked in to reduce drag..?...or a combination of both...i would have thought that cranking the boost would have offset the price differnce in purchase price of fuel..

weird..!

ryn004

Was it the same time of day? The car can be more efficient when the air is cold. Was it a windy day? Maybe the wind was against the car on your way.

TonyBurns

iTrader: (3)

Ambient temperatures can add/reduce to the fuel consumption.

Tony

RJ1

Where did you get SUL at that price, very cheep, still 121.9p cheapest in this area !

timmy2take

iTrader: (7)

The fuel gauge can be all over the show on Subarus i've found. Think the only way of really telling would of to of done the said journeys on full tanks and seen how much you needed to put in at the end of the journey.

munna

sorry i may have got my prices wrong...the tesco 99 was from uhum...bradford 7 Great horton road..priced at...(just checked my reciept..£116.9 p/l..)

lost the reciept for the shell one so cannot confirm the price..(Has the price come down again?)

they were changing the prices yesterday so there was a que as the attendants changed the price board...

this was at 7pm last night..

drivinh back up..weather was fine, no wind..muggy..same as the drive down..except the time which was 5pm for setting off time

only a difference of 2 hours

timmy2take, true..i may just have to do this...

munna

Free UK fuel prices. 9,746 petrol stations covered - PetrolPrices.com

according to the above site,there is a place in bradford that is selling SUL at

115.9 P/L....

Gear Head

iTrader: (2)

Absolutely useless infomation I'm afraid. Unless you do a full fill and work out the mpg, you will never get a true reading.

munna

you do realise it was never meant to be a mathematical question..?!..just a random question...!

to work out true MPG, you would have to check tyre pressure, wind speed(in direction of travel..)..car speed, incline, decline's..slipstream...yadda yadda..

all it was, was ageneric question.....with all the variable i had at hand...

chocolate_o_brian

iTrader: (22)

lol try having an old school pug

can loose a quarter of a tank on a sharp left hooker or uphill stretch, then suddenly fill up on right hookers and downhill stretchs

brilliant

MrRA

What question are you asking as I'm failing to see? All you have done is stated the outcome to a rather crude test. If had the run the car on a few tanks of the same fuel before switching to a different brand you'd have probably seen a different outcome.

Gear Head

iTrader: (2)

Precisely. Didn't mean to sound rude, but there usn't anything else to say.
To work out MPG, why would you need to measure wind speed and tyre pressures. Just set the pressures as you would normally, fill the tank, zero the trip, then fill up and calculate the mpg when you next fill up.

How hard is that?

SqeekyMclean

Or you could just put it on a rolling road

Blueblaster

I can see what you're getting at so I'll give you an answer. From what I remember the boost used to kick in at about 80-85mph on my 05 STI. If you've changed the point at which the boost kicks in to a higher rpm then it is quite possible you used less turbo boost on the second journey. This is the most plausible reason why remapped Scoobies get better mpg despite being more powerful. As for the wing mirrors, it will make a difference. When the McClaren F1 set its world speed record McClaren wanted to take the wind mirrors off to reduce drag, but decided not to because the car would have been non-standard. I doubt it will make as much difference as changing the boost although you never know because the difference in mpg with and without my ski rack on the car is massive - something like 15-20%.

HTH

MrRA

Surely you would want boost at a lower rpm i.e. less lag?

Blueblaster

Nope, not for economy. Make it kick in higher up the rev range so you only use it when you really need it and not when you're just trundling about.

As for the remapped cars I think it is generally accepted that higher rpm = higher power so I guess (and this is a guess) that most remapped cars don't just have the boost turned up, but also have the point it kicks in adjusted. You wouldn't want it coming in too low in the rev range because tonnes of boost dropping on and off as you pootle along in traffic would be seriously tiring. Maybe someone with a quality remap can comment on my theory?

BooSH

Back to Tesco Fuel, I've stopped using it after a work mate had terrible problems with his ECU light coming on, he'd took it into the garage and they couldn't find anything wrong with it, he did some research (it was on a peugeot) and it turned out it was **** fuel that was making the light come on believe it or not, and honestly since he stopped using tesco fuel it's not come on again. I'm also a V Power convert (i apoligise to all who i said it was a waste of money) my car runs so much better and starts up like lightening since i've ran a few tank full;s through, and will only put v power in now.
I've recently had a new shell garage open up about 2 miles away, ifilled up today and it was 121.9 a litre the other one a normally use on the way home from work is normally 126.9 a litre so i was well chuffed.

MrRA

Since when would you want to buy an Impreza for economy??

What?

Blueblaster

This is a thread about fuel economy and Imprezas. No one, even the pathetic dipsticks that report my posts can claim I'm trolling on this one. So don't drag this thread into a "if you want good fuel economy don't buy an Impreza" know-it-all slanging match. The fact is, if your boost kicks in higher up the rev range then you won't use it as often and therefore you should get better fuel economy. If I'm wrong then explain why so that I learn something. Otherwise shut up. What a useless post.

stair

Round my way tesco 99 is 3p/l cheaper than v power, car runs fine on it BUT is 5%-10% poorer economy so no advantage. run on v power given the choice and since tesco garage and shell garage same distance from home thats almost always

others have reported different results!!

I believe that a major factor is that ethanol added to the tescos 99 reduces the energy content/litre hence more fuel required to perform same work

Stair

GC8

Certainly: it increases the RON rating / resistance to knock but it has a lower calorific value, so you get less power. The trade-off comes with its ability to stand more advance: the net result may be that your engine produces more power: or less.....

MrRA

Since when has anyone mentioned you were trolling now? Calm down and wind your neck in.

Simple fact is this, Scoob's are useless when it comes to economy. A remap can you provide you with greater economy AND better performance as the fuelling and ignition are improved. If you want economy go buy a diesel or a smaller engined car. Having the boost come in higher up the rev range is simple ruining the whole driving experience of the car, making it WORSE than the factory map. The whole point is try and keep turbo lag at a minimum. Tit.

munna

hi

wow, sorry about the lack of no replies..i thought this thread had died..!

lots of interesting comments and thoughts..to be honest the initial thread was started as just a nonsical thing that i noticed on the journey down, and then back up...differenc just being the type of fuel used, and the wing mirrors being pushed in..

well, if truth be known, i have been pootling around from one career, to one business, and back home, with a few lunch time runs to asda, and back..just the normal stuff

and my needle has dropped to half way between the quarter and empty line..so a hot run is the order of the day tommorrow..down to fumes..and then a full tank of tesco 99..with the apexi running at number 3 boost..(1.0 bar)...i shall see how long she lasts on the daily slog..

thanks for all the feedback guys...the jury is still out on the V-power vs tesco 99...look on the bright side..they both beat that gunk that is BP...

Blueblaster

I'm sorry if that came across as a little short. I was tired and was getting browned off with.....well...whatever....

This could have been a really interesting thread talking about drag, controlling turbo boost and the properties of different fuels. Instead it's been killed by people who seem to want to mate with their Impreza before driving it in the least economical, most antisocial way possible.

Don't bother responding to this post because I'm not interested. In fact, is it possible to infract myself to save someone else the bother?

munna

ha ha....dude what you have said is so true....never mind..i shall conduct my own experiments..post them...and then have somebody analy rape my post....



!!!....

dunx

iTrader: (3)

Surely Saab found that the most economical way is to get up to a steady speed briskly, not chugging through the gears in "eco mode".

As an STI is doing 75 mph at 3000 rpm in 6th gear, you don't need to raise the boost threshold (?) as you will be breaking the speed limit anyway

Managed 25 mpg on a trip to RE Motorsport yesterday, at a steady 79 mph.

Always try to stick to V-Power + CVL myself.

DunxC

PantsUK

iTrader: (1)

When I had my remap done I specifically asked (if possible) for the boost to come in no earlier as although it's not an economical car I didn't want it to be even worse and as I can sit (on a private oval track yada yada yada) at 85ish and still be under the boost threshhold this works perfectly for me.

On a remap fuel economy note (all on vpower with mixed driving mway and a/b roads + town driving) before remap I was getting 230 to 250 I'm now getting 280-300 which as far as I'm concerned is fecking awesome (for a scoob)!!! (Works out about 27mpg by the way ...roughly ...)