Hey all. Just hopeing to start a discussion on getting better mpg from our impreza.

Dont comment saying that you shouldn't have bought an impreza if you cared about mpg. That's not helpfull
The fact that our mpg is so low means there's the biggest room for improvement.

This thread isnt about driving style. Owning an impreza and then driving like your grandad really is pointless. I'm interested in mods. Like aerodynamics or similar

 

Other than having your car serviced regularly, tyre pressures checked and running a thinner oil there is not a lot you can do apart from avoiding short journeys and driving with an egg under your right foot.

 

I've read of late on this forum by a member that a rear ARB helps with MPG and they can get an Impreza to do around 50MPG......

 

Well no matter how I drive I can't get more than 24mpg and worse I can get is 19mpg

 

Aerodynamics only count 70mph+.

Ensure that it's well serviced, obviously drive off boost and you should see 30+ MPG.

I get about 25 MPG and drive it like it should be when road/traffic conditions allow.

 

I average about 25mpg at the min but that's because i'm in the sticks so I get more opportunity to drive spiritedly when I actually go somewhere, only drive about 3 times a week though so don't use much fuel.

In the uk I get around 28mpg around town pootling and 33mpg + on a run at 70/80mph.

Forget aerodynamic mods, best mod for fuel consumption is a boost gauge.

 

Well just shows I must drive like a proper plonker. I get about 8mpg. Glad mine is only a toy I couldn't afford to have mine as a daily driver. Think I have it up in the high teens once or twice but never 20+

 

Yes regular servicing and tyre pressures. I average 33mpg it went to 35mpg the first couple of tanks when try rebranded to nitro. Back to 33 now

 

Is that with 500bhp and on track?

 

Nearly 500 it's 450bhp 480lbft on a forged 2.5. I'm sure all you guys must be working out mpg wrong as I don't know anyone who gets 30+mpg even on the motorway. Most get about 22mpg and that's taking it very easy. Real world driving is more like 18mpg. Unless you guys all drive the new diesel impreza

 

It's easy to work out MPG, just put 3 gallons in the car when the fuel light comes on drive until the light comes back on and share the miles you've done by 3. I usually clock up 100miles off circa £20.

There are plenty of things to do to save MPG, I'm getting 33mpg around town and up to 40mpg (have seen more but the journey involved more downs than ups) on journeys that aren't stop start or involve fuel sapping tight corners.

What I'm hoping to do is crack a 40mpg long term average. At the moment it stands around 32.5mpg and that involves city centre and illegal street racing whilst smoking crack..

I'm going to get some branded harder tyres next and look to save more weight here and there. (Including my fat 15.10 ***.) Not running on 2 cylinders in the future might also push me towards a 40mpg rate.

I find driving style doesn't really matter in mine as a quick blip to 60 on a long stretch can see me cruise to the next junction on the lean over-run.

On WYSCOOBS there was a heated discussion about cruising revs, most claimed to travel around town at 30/40 in 3rd at around 3000rpm, I tend to cruise at 30/40 in 5th at 1500rpm. This claim also brought ridicule and astonishment.

I can imagine I'd get lambasted for saying that I don't pre-rinse when I wash Billy.

 

Price of fuel, litres used and miles traveled isn't too hard to work out! Plus my mercedes sprinter uses around the same litres to miles traveled and that tells me the mpg on the computer which is the same.

 

In car guides it usually lists the Newage STI using 25mpg and the WRX 30mpg, what is the main contributor to this? Power, weight, chassis set-up, map, tyres, gear ratios?

 

Used to get around 18-22 around town in my blob sti , went on a run down to devon once and got 34 ish , sat at 70 mph most of the way down

How anybody manages to get anything over 25 around town is a huge shock to me , I couldn't get that if I pushed it around town

 

Having a 1260KG Newage helps me and a TD05 that doesn't spin until 5k. Bloody TD04 used to whistle at me to wake me up on a morning. That's a metaphor btw Tubb's clique.

Hasn't the parasitic RA Dunk sent Tubbs a text message yet to get him up for this epicness.

 

 

The turbo and map basically. The sti is a car with economy in mind. The Wrx appealed to a different market, so the map was a bit more eco friendly. Plus you have a smaller turbo which demands less air and therefore, fuel.

You will never get 40mpg in an impreza. If you are, you are working it out wrong. Don't bother with the 3 gallon fill when the light comes on to work out mpg. The point at which the light comes on can vary depending if you brake or corner fast, sending all the fuel away from the level. Meaning you actually have more fuel in your tank than what you thought, giving you favourable mpg readings.

Fill tank to brim, re-set trip, drive until you need to fill up again.

If you have done 250 miles and you put in 45 litres to fill it up, calculation is:

(250/45) x 4.545 = 25.25mpg.

Working it out any other way means that you are just guessing.

Best I ever got was 37mpg in my 99 UK Turbo. 30 degree heat, 100 mile drive at 55-60mph.

In my 05 WRX running nearly standard power, I got 30mpg again on a motorway run but driving at 70-80mph last summer. Usual around town after that was 27mpg, then winter hit and I'm getting 23-24mpg.

Exactly as expected to be honest.

Back to the op, I think you need to get a handle on aerodynamics before you start taking your Impreza to the wind tunnel.

As already said, check the basics such as tyre pressures, fresh oil (thinner oil will give better mpg but may not be great for protecting your engine at hot temperatures), tracking, brakes are not dragging and most importantly, your driving style! Anticipate the road better, try to avoid braking or using boost. If you are doing all of this, you then have to ask yourself..........

Why the hell do I own and Impreza?

(sorry, had to get it in there!) [

 

Was it just Millers Nanodrive CFS that gave dramatic BHP increases or both CFS and EE? I was thinking of dropping down to 10w40 but the CFS only does 5w40.

Also would DEI Radiator treatment save me much fuel? It states 50% quicker engine warm up time and slightly reduced operating temps.

 

Seriously fella, you are clutching at straws.

 

I don't brake or corner fast, the light on mine is pretty consistent tbh and my calcs match the OBD2 readers findings on the enhanced MPG calculation setting. Even when I put £40 quid in the calcs are similar, the light being 1 or 2 mins premature will only knock calcs out by a tiny percentage anyway at 6 gallons.

The weather temp effecting MPG is new to me though and it's quite a revelation, judging by what I'm discovering my mpg could trouble 40 this summer.

TBH doing 33-40mpg on long and short trips (I did claim over 50 once but I recently discovered my OBD2 reader sticks on a certain uphill road every time for some reason) saves me money for more mods! It also saves my driving license and keeps the car supple for drag days!

I only drive at the weekends though.

 

People said that with my weight saving exploits at first. No car the wrong side of 400bhp could touch a 260bhp Billy away from the lights.

Spare wheel gone guys "what about when you get a punner?"
Aircon gone guys "but you will get hot and sweaty"
Bucket seats gone guys "your back will be knacked on long journeys"
Lost 3 stone on diet chaps "but your Taybarns exploits were stuff of legend"

 

Car stereo ditched boys "But, but, but I can't go a day without listening to White Feathers." - Tubbs.

 

RS Matt, you are a Subaru legend, beating 400bhp subaru's with just a simple weight saving on a already super fast WRX!!

Have you thought about leaving a quarter tank of petrol in a time, Even more weight saving!!!

 

There's a reason I work the mpg out with 3 gallons.

What would be quicker to 60mph a 300bhp WRX with 150lbs of torque or a 150bhp WRX with 300lbs of torque?

 

The fact that you didn't realise that ambient temperature can effect fuel consumption says a lot about your knowledge of the internal combustion engine. The above statement confirmed my thoughts.

 

Not necessarily true, I believed only excessive hot (25c) or cold days (-5) might have a bearing on efficiency and that I'm surprised anybody knew a 5c increment could increase or lesson mpg by circa 8%

I'm sure you can provide detailed science Tubbs MKVI.

 

Ahhh cess pit I love the way you need to refer to me in every post.
Do you love me or want to be me?


Trolololololol

 

Read this.

http://www.metrompg.com/posts/winter-mpg.htm

It isn't exactly a new discovery but common sense. I get 5-7mpg less doing the same journeys from the peak of summer to the coldest months of winter. Air is colder in the winter and therefore, more dense, so the car ecu throws in more fuel to achieve the correct mixture and prevent the engine from running lean.

 

Says the man who slags off anyone that doesn't have 'S'exually 'T'ransmitted 'I'nfection!

 

Yup and as I keep telling cess pit...

I don't own an impreza of any description,doesn't change the fact I know the wrx is the poor relation to the sti in every respect.
I have driven a wrx on many occasions as my Mrs still owns one and its slow compared to an sti despite cess pits claims