Fuel Efficiency - could be a boring read for some

[MMorbo]

I make regular trips between Brisbane / Armidale down the New England.

It is a little over 400k... undulating relatively reasonable roads for anyone who has not done this before...

the trip is usually done with 2 in the car, and a small amount of luggage... up until now i have been averaging (according to the cars trip) 8.5L/100k down, and 8.3L/100k back... (down is up the range, so i expect about .2L penalty)

Average speed is pretty consistent at around 96.2-96.8 km/hr...

...anyway down this thursday night it was just me in the car, average 95.2/kmhr (some shocking weather) and some road works which left me as expected at 8.5L/100k... (first long trip with new down pipes)

The surprise came when i headed back, average speed was 97.8kmhr, but my fuel economy ended up at 7.7l/100k.. never seen it this good before...

now as far as i can tell the only difference that i made on the trip back was i had the cruise control set to 108km/hr, where as generally i keep it on 100-105km/hr...

all trips are started with a full tank... and the latest trip down / back the over all vehicle weight was 8kg lighter on the trip back... (it was an overlocker my wife asked me to give back to the inlaws...)

so the question is... has anyone else noticed a fuel efficiency "sweet spot" around the 108-110km/hr mark.. or is my computer busted..

or could the several 0-100 tests i did on a few quiet back roads some how have freed up the engine...???

(please note 108 was on the open highways... all speed limits were obeyed around towns)

[lovesacdc]

Could be due to a tail wind, no air/con, windows up. Wind resistance could be the difference.

[John_01]

Maybe your car's efficiency is improving as you get more km on the car.

I don't keep any notes, but I've done the same trip twice in the 135i. Sydney to Armidale, sleep, then to Surfers and back. I have noticed that travelling at higher speed as you wrote dosen't seem to have any penalty in fuel consuption. 100km/h is barely moving for our cars with so much torque and power so I personally think it comes down to smoothness and other factors. Higher speed for travelling on gentle inclines could even be more efficient due to a bit more load on the engine.

[BBK]

Air con used?

[MMorbo]

Originally Posted by lovesacdc

Could be due to a tail wind, no air/con, windows up. Wind resistance could be the difference.

Aircon was on for both trips... Ambient temp was similar so it should have been consistent in terms of usage.

In terms of k's car has now done just over 30,000. I have only put 12,000 into it which is pretty much made up of 5 trips down and back.

Would be great to repeat the 7.7...

[3lucidus]

your driving a diesel though sam... you'd expect more l/100km

[gazz]

Originally Posted by Samuels

Hey bros

I went to Newie on the weekend and I got like I dunno 7.2 or something and that was cruisin an ez 125.

Dunno prob the fact my ship is non turbo ay

Peace out yo
Sam

G'day Sammers, ow ya goin mate? Crikey, 7.2 is flippin good at that rate of knots.

[crystaweizen]

Over i here in the us I believe my sweet spot is about 75mph on flat roads. Get 30 to 40 more miles per tank so about 360-380 miles on a tank of 91 octane

[Gemballa1980]

Wouldn't it be the down pipes? Since you said it's the first long trip you've had with them?

I noticed better crusing MPGs since the catless dp's went in.. And then again (not quite as big a jump) when the FMIC and charge pipe were slapped on.

???????

EDIT: never mind.. You had them on the way there @8.5l/100k

[gazz]

Originally Posted by Samuels

Dunno if ya taking the piss bro but yeh I think it was pretty ok

Takin the piss! Jeez Cobber, try to be a helpful cove and look at what I get.
You don't know Christmas from Burke street if you think I'm having a go at ya.
Blues are not my bowl of rice. Shit stirring bastards are like a brown eyed mullet on this forum.

Cop u later.

[choppedliver]

We did a syd-canberra run with the roof down and on cruise at ~120km/h (really more like 116km/h) and got 7.8 or something like that.

When I went slower another time (110) I only got 8.x. not sure why.

B

[gazz]

Oh all right then.

Anyway, I'm a little uncertain. Do you have a 130i wagon with a 123d badge from your brother bro on it or is it a 123d hatch?

Because I would have thought you would do better than 7.2 / 100 from a diesel. My old 335i would eke out mid 6s on an albeit restrained freeway trip. Then again our 1 series seem to have the aerodynamics of a brick dunny.

I think my wife's X3 does low 7s on a trip and it has the aerodynamics of a public brick dunny.

[froop]

Originally Posted by Samuels

Yeh bro no worries

My brother and me swapped the badges round so I got 123d on the back

Why?

[GJA003]

Originally Posted by froop

Why?

Because his name or his brothers name is Richard ?

[MMorbo]

Originally Posted by crystaweizen

Over i here in the us I believe my sweet spot is about 75mph on flat roads. Get 30 to 40 more miles per tank so about 360-380 miles on a tank of 91 octane

At the 120 / 75 mph one of the other posts get similar results...

I should add that both down and back was using. 98ron... The way down is always filled up at the BP near indooroopilly shops and the way back is caltex... Shouldn't be too much difference between the two brands...

Anyway could be a million variables... But good to see others are noticing improvements over 110

[MMorbo]

Originally Posted by choppedliver

We did a syd-canberra run with the roof down and on cruise at ~120km/h (really more like 116km/h) and got 7.8 or something like that.

When I went slower another time (110) I only got 8.x. not sure why.

B

What are you running mod wise.

I get the FMiC next week and will switch to map 2 on jb4 then... Should it be worse or better fuel at 14psi? Not fully across that technical side...

[Zuzu]

Originally Posted by MMorbo

What are you running mod wise.

I get the FMiC next week and will switch to map 2 on jb4 then... Should it be worse or better fuel at 14psi? Not fully across that technical side...

When I had my 135i vert with JB3 tune and exhaust mods, I would set the cruise control on 115km/hr on my trips to Wagga Wagga.

Average around 7.8 to 8.1ltrs/100km..

[Zuzu]

Originally Posted by MMorbo

What are you running mod wise.

I get the FMiC next week and will switch to map 2 on jb4 then... Should it be worse or better fuel at 14psi? Not fully across that technical side...

When I had my 08' 135i vert with JB3 tune and exhaust mods, I would set the cruise control on 115km/hr on my trips to Wagga Wagga.

Average around 7.8 to 8.1ltrs/100km..

[Nugget]

Can anyone beat (get worse than) my fuel consumption?
http://www.fuelly.com/driver/nugs/135i

[gazz]

Just filled up - $174.9 per ltr

[choppedliver]

Originally Posted by MMorbo

What are you running mod wise.

I get the FMiC next week and will switch to map 2 on jb4 then... Should it be worse or better fuel at 14psi? Not fully across that technical side...

None at the time. When I cruise I have it factory mode (now) anyway unless I need to overtake.

B

[3lucidus]

Originally Posted by gazz

Just filled up - $174.9 per ltr

thats just rediculous