fuel economy 318is v 325i

[baybee]

Hi
I have been told by almost every e30 head I know that there is very little difference between fuel economy of a 325i and a 318is. is this so?
In black white, 318is is significantly better and makes for a better every day car but every time I hear 6 pot drive by I feel like less of man.

[kam-325i]

you can easy make 30mpg in the 318is but not in the 325i....

[polsta]

i went from an is to a 325, heres my thoughts/expirience

on a run/motorway trip there wasnt a lot in it, ive achieved 34mpg in my 325 on 2 round trips of 50 miles town-motorway-town driving like a granddad, the 318is was slightly better

the is is a revvy engine...if you drive that keeping under 3.5k revs, changing gear at the right time , then its good on fuel...drive it about hard and it will use more obviously

but around town, the 318is definatly better on fuel, a 325 can be guzzly if you start putting your foot down , as its a heavier car, stop,start,stop, start around down with lots of accelerating and breaking, it gets juicy

put it this way....you definatly find yourself putting in more ££ in the tank

BUT...you get a much more better feeling when driving, the 6 pot roar/sound, feeling when accelerating , far far superior to a 318is , when cruising along say on the motorway at 60/70..put your foot down and it gooooes and shifts a lot quicker than the is

i actualy owned both the is and 325 at the same time parked outside, could of kept them both, i drove the 325 arounde for a few weeks...and got back in the is and ...it killed it for me, when you rev the m42 and drive it...it feels like you have nothing under the foot compared to the 325 , the roar/sound of the engine, feeling it rev , and driving the is after felt like it had no real guts , 3 people with you in an is...it struggles to move really, not the same in a 325

you get what you pay for...its more juicy, but better to drive and puts more of a smile on your face when driving, but i loved my is dearly,my 1st e30, a good introduction to e30s and a steppping stone to my 325

if i were you....it would boil down to this.... if you do a lot of miles, a lot of nipping aroud town and generaly in your car a lot, it would all come down to finance...just having a 325 as your daily and only car and doing alot of running about, it would be maybe 33%/ third ?> (at a guess) costly over the 318is , and maybe isnt a good choice , unless you can just fill her up regardless of fuel costs.,..which then comes down to your job and means

if you use it all the time and find yoursef thinking "fking hell this is exxpensive/juicy" then you find yourself not driving it how you really enjoy it and want to drive it, coz your watching the fuel

ideally its a better 2nd car with a cheaper run about along side it for the nipping around

i think i read somewhere, that a 325 engine is best when warmed up to full temerature, so nipping around in it not getting to temperature, makes it thirsty

[baybee]

you only live once, I think i will go for an m20b25 conversion on my IS. Would have gone for m50/m52 conversion but I dont like the way they sound.
So locally what mpg would I expect from a 2.5 engine? in the IS, the OBC shows I do 33.4mpg but I recently borrowed it my brother, who has 2004 impreza 2.0 Turbo and gets 18mpg, and he is saying my mpg is more or less same as his. I have driven an astra 1.6 which on paper is 38mpg and it feels its far far far far more fuel efficient. Any thoughts on this?

[anothere21323i]

I can only give you some recent personal experience with my 325i touring, as I've never driven an IS, but on a long motorway trip I can coax it over 30 mpg but that's driving very, very steadily. If you drive a bit harder (overtaking etc), it regularly drops below 20. I use it every day and do quite a few miles, and am spending easily 100 quid a week on petrol.

Hope that helps?

I'd suggest if you are going to go to the effort of doing an engine conversion, find out what sort of economy you'd be getting from a M50/2 as they are a much more modern engine. Plus you already have the correct gearbox to do the swap into your IS.

[Simon13]

a 325 doesn't ever do 34mpg. Thats bullsh!t. If your ever getting a proper 30 mpg out of your 325i then you'll be getting 400 or so miles out of a tank. Waits for tumble weed. You'll need a long motorway and cruise control to do it or you'll be tailgating artics at 56mph

However a solid 24-28 mpg combined is possible with some restrain.

A 318iS will do nearly 30 round the houses and if your really gay nearly 40 on a run.

Having had a 325i sport and 318iS at the same time, i sold the 318iS on in the end.

[polsta]

34mpg over 100 miles i kid you not, i posted it on here last year what i put in at what cost and what miles , and was told that was 34mpg, and was told thats achievable

i put £20 in an empty tank and got to work and back twice- 4x- 1.5mile town- 21 motorway-3 or 4 miles town

at night so little traffic, same journey in rush hours/daytime would be a different story

like i said was literaly driving like it was a use as less fuel as possible journey and not enjoyable as such,although fun in a way, once on motorway at either 2k or 3k revs i cant remember now whatever it was using the mpg gauge on over the 30 line as far as pos, keeping foot planted rock solid in position for 21 miles , it would be at say 55mph , letting the car naturaly increase speed to up to 80mph downhill and down to say 40mph uphill (not big hills mind but just natural motorway ups and downs)

lorrys will overtake you at times going on slight uphills, then it changes and 5 mins later your flying back past them at 80...and youve not moved your foot at all

but golden rule was dont move the foot at all, keep it solid as to use no extra gas accelerating to go faster and that needle above 30mpg at all times, play about with it youl see what i mean

try it

[e301988325i]

best on petrol out of my 325i was 32mpg on a tank and that was trying very hard!!!!

There's a simple answer, a 325 on LPG is cheaper on fuel than a 318is on petrol, win win.

[MattTheHat325]

How hard up do you have to be to drive at 40 on a motorway? I'm a lorry driver and that would really aggravate me, especially if we were playing musical lanes with each other! I know what you mean though mate, only very slight throttle input on a 325i sees the mpg plummet.

[Alex]

my 318is was pretty good on fuel, the 325i killed me, however travelling mainly back roads to work everyday killed me, i cannot drive sensibly on them.

i would say if you want an economical car thats fast there isnt an e30 for that. if you dont do many miles or an e30 is a second car you want a 325i

I work closer to home now so bought a 325i again to smoke about in

i got 30mpg out of my 318is no matter how hard i pushed the turd. i managed 20mpg one day in the sport, that was a good day, mainly 15-18 however it was on motronic 1.1 the later engine mangement is suppose to be better for fuel ?

[polsta]

How hard up do you have to be to drive at 40 on a motorway? I'm a lorry driver and that would really aggravate me, especially if we were playing musical lanes with each other! I know what you mean though mate, only very slight throttle input on a 325i sees the mpg plummet.

i did it to see how far i could get out of £20 trying the absoloute hardest, on a "normal" run i could put in £15 a trip=£30 ,to do that , if driving hard then £20 a trip i should imagine so you can see really its possible the trip in the same 325 driving different ways could be double the cost, but also interesting to see how the car slows/accelerates and to what speeds on its own natural course of the road

[verde]

when i was on about the 2 litre motor in my white car most people on here said " put the 2.5i in it, ul get more power and better fuel consumption " ?

[suchy]

I don't think there's a hill long enough to coast down to achieve mid-30's with an M20!!
One would have to be VERY delicate with the throttle to see 30mpg on a long run

These engines are from a past age when filling up wasn't a prison shower scene. They make no sense as a daily driver anymore unfortunately

If you do decent miles each week, it's cheaper to run another car...

[nickphine]

I used to be able to get a genuine 50 mpg door to door in my 2.0 litre 8 valve MkIII Golf GTI by slip-streaming everything in sight up the motorway, it turns into a game if you're really bored. So you'd have to think 34 is possible in an M20, maybe?

As for M20 versus M42, I've had both, and the M42 had to go in the end as it feels really wet in standard form. I've got a M20B28 in mine now with a 4.45 diff so I'm afraid to even try and work out how many mpg I'm getting. Much livelier though now, slightly wayward with the extra weight after the super neutral handling of the M42 engine in the same car.

We don't have E30's for their economic prowess in any case so it has to be the M20 option and hang the expense...

[suchy]

I could get 38mpg out of my 8v MkII easily, but never going to get close with an M20 EVER

[TheDutch]

A 318iS will do nearly 30 round the houses and if your really gay nearly 40 on a run.

You'll be pleased to hear I tend to average at least 37mpg in mine mainly commuting into London, and mid-40s on a run is attainable. Over 500 miles on a (55l) tank has been done a few times, and that includes frequent stopping for all the sausage on sausage action. As good as the M20s sound, for me it's just not good enough to make up for the drink problem.

[HairyScreech]

I can get a sound 32mpg from most versions of the m20 provided the car is in good fettle.

I think its got a lot more to do with driving style than the actual car, as im sure i could make a 318is drink like an m30 if i drove it badly.

Have regularly done 120 miles mixed m4 and a/b roads on 16l of fuel, thats 7.5 miles/l, which if im not wrong is almost bang on 34mpg.
Now if that was really only 28mpg and i used the reserve as well then i would have been getting home with 1l left in the tank, which i dont even think would wet the pump.

Every time i do the run i put ~16l in and always make it back with the light coming on between 8 miles away or not at all.

Now i know going light to light is not reliable but having done the same journy at least once a month for 5 years iv never seen worse than 28 and that was in rush hour.

My real world (if not particularly scientific) experience is backed up by the obc on mine which was always 100% right (up until it stopped working for no reason )
Now as for the obc telling lies well thats hogwash, the obc knows the flow rate of the injectors, the opening time and the speed of the vehicle, thus provided the car is in good fettle and the obc hasnt been fucked with will give an accurate account of the mpg.
(well more accurate than going light to light or brim to brim and reading the odometer will ever be.)

The cripling thing is when i started i was paying ~£15 for those 16l each way, now its more like £21.50 each direction.
Meaning a trip home that used to cost £35 with bridge toll is now nearly £50 with the increased tolls meaning im getting to see the friends/family a lot less.

VIVA LA LPG!

edit - for clarity i do average fairly shit mpg if i drive in a manner than involves enjoying the drive and not saying "fuck it iv got to do this for 2 hours at least no point in pissing about".
the best/worst iv had is 11mpg, for clean licences sake i wont say how.
around town im also getting a lot worse than that, early 20s at most, which is where is m20 falls over, if it doesn't get to stretch its legs then it will sulk and binge drink.

[HairyScreech]

i just did the mpg i get to uni a week, put £20 in at the start of the week and end up doing 12mpg,
Thanks labor council and your fucking traffic lights.

[askjeevesplease]

My sport does around 23-24mpg. Id like to know how the above guy is getting 34mpg. Even my 318i saloon doesnt do that, and yes i drive like a gay but like women!

[suchy]

Downhill all the way!!

As Screech mentioned, around town an M20 takes the p*ss on fuel, mine will see low-teens mpg on stop/start traffic when things get really bad!!

[HairyScreech]

it is a touring which helps a lot, the drag the rear of the touring produces is quite a bit less than a normal saloon, the tech 2 spoiler will make things worse as well.
this is reflected in the Cd of the two body styles.
so a saloon will be worse on fuel.

but still as above on a run i have never been outside of the 28-34mpg range unless iv been driving like a dick or the traffic has been awful.

personally i put it down to a healthy engine with good compression, engine management function as it should and driving style.

when i had an air leak making the car over fuel i dropped to about 25 combined, it put the fueling out of spec enough that i could smell fuel inside the car at idle.
so generally bad mpg is a sign of there being an issue somewhere.

iv also found accelerating gently to be worse, due simply to the amount of time spent in the acceleration enrichment part of the ecu map, you can see this for yourself by depressing your foot just slightly more than is required to hold your speed.
the 1.3 seems to have a very juicy enrichment and you can see the needle plummet when the ecu thinks you want to go faster.
a fine throttle foot and a bit of practice makes avoiding the acceleration enrichment map easier.

i know the theory says acceleration as gentle as possible then steady state will be best, but thats only ideal physics and goes right out of the window when you take into account the way an engine is fueled, the ve fluctuations of an engine and the gearing of a vehicle.
different cars need different techniques and the combination on a 6pot e30 seems to like getting to speed fairly swiftly and sticking with it, be too gentle and the extra fuel added by the ecu more than offsets the theoretical ideal.

[polsta]

My sport does around 23-24mpg. Id like to know how the above guy is getting 34mpg. Even my 318i saloon doesnt do that, and yes i drive like a gay but like women!

i dont "get" 34, ive achieved 34 ...and driving how i explained above.

[askjeevesplease]

Ok i do apologise i thought you said i get 34mpg on a run like all the time.

Why drive your sport like a grandad? Buy a 316 or a Volvo for that.

[E30RKD]

my 325i is very heavy on fuel but it all depends on your mods like mines got a full stainless steel manifold and back box which does make it heavy on fuel but if i drive it seneiblely it not too bad

also depends what fuel you put in i mean super market fuel i feel burns super fast butn in my e30 i have always used shell fuel.

[askjeevesplease]

The type of fuel makes no difference to these 20 year old engines regardless of mods. Could argue that on a new car.

[suchy]

Actually Tesco fuel returns less mpg!! Proven on long term roadtests!! 'Normal' fuel vs Super fuels = no difference though

[HairyScreech]

i cant really decide either way.

obviously optimax will give no gain over any fuel that meets the requirements set out in the ecus program, as there will be no accounting for the improvement over stock.

however i do think when it come to shit or stale fuel there is a difference,

my thinking being that the ecu will put in x amount expecting it to make x amount of power, and it wont change that unless you put your foot down more, at which point it will enrichen the mixture.

now if the shit fuel is burning poorly then the car wont be making full power, which means your going to account for this by putting your foot down a little further thus using more fuel.

so im kind of in the camp of "as long as the fuel is good enough for the ecu/engine spec it will make no difference".


edit - schuey i was actually thinking of tesco fuel when i wrote the above, i am sure i have experienced it and have even mentioned it to the mrs,
i didnt know there was an actual study done into it though.

[askjeevesplease]

Are you following me

I stand corrected then.

[HairyScreech]

yes,


by the way that's a nice top your wearing.





to be fair you might be right, that's just my thoughts an theory on it, i could just as easily be wrong.

[suchy]

Yeah I don't know why Tesco fuel returns less, but it's consistently less?? I'm not just talking about a one tank test, I'm talking about over 2 or 3 months to get consistent results!! Sainsburys and Asda are the same, Optimax doesn't seem to make much difference even though I'm mapped for it (can't justify spending the extra to do a decent long term test) and will be doing a Shell test when I start doing more miles in the next few weeks

[askjeevesplease]

yes,


by the way that's a nice top your wearing.





to be fair you might be right, that's just my thoughts an theory on it, i could just as easily be wrong.

Errr that was meant for Suchy. nevermind

[HairyScreech]

yes,


by the way that's a nice top your wearing.





to be fair you might be right, that's just my thoughts an theory on it, i could just as easily be wrong.

Errr that was meant for Suchy. nevermind

Bugger, reveled my hand too soon.....

[suchy]

Are you following me

I stand corrected then.

No you're just appearing on most threads at present!!