[constipated]

The biggest improvement that I have been able to achieve in my driving, economy wise, is to always slip it into 5th as soon as it can cope.

I've been wondering about this. I do miss that the trip computer does not have instantaneous economy.

Tonight on an 80km/hr stretch using cruise control, I could choose between 5th gear at about 1900rpm and 6th gear at 1600rpm. The engine was not noticeably labouring in 6th.

I reset the trip computer avg consumption in 5th gear, the first value that came up was around 4.7-4.8L/100km. I then repeated it but in 6th gear, reset the avg consumption, and the first figure that came up was 5.1L/100km.

Would be great if others could try this out if they have trip computer. Maybe at 70km in 4th/5th gear if you've only got 5 speed.

My question is: for best economy in the diesel, is it better to keep the engine revving at around 1900rpm (the base of the torque plateau) or at lowest comfortable revs.

In my previous petrolcar  that had an instantaneous consumption measurement, it was clear at 60km/hr that 5th gear was more economical than 4th gear. It's funny with the gearing, 5th gear would only struggle at around 50km/hr, yet in the i30, 50km/hr is really the bottom limit for 4th gear, and I wonder if 3rd gear would be more economical.

[unfamilia]

  I reading people complaining for 6 lt per 100kms sorry.

My suby city driving got 15 to 16lt per 100 on 95 octane  :-\

So anything under 8lt per 100 from my crdi auto city driving will make me 


I know cars are advertised on lt per 100 but any thing in the 5's or low 6 for manual and 7 for an auto city driving would be pretty damn giid real world.freewAy that should drop as discussed above

[rustynutz]

My question is: for best economy in the diesel, is it better to keep the engine revving at around 1900rpm (the base of the torque plateau) or at lowest comfortable revs.

"Seat of the pants" driving tells me to keep it up around the 1800-1900rpm mark (or higher) where you'll also get instant acceleration when you need it.

[tombodombo]

My impression is that keeping revs below 2000 is the way to go but I have no fuel computer.

[accim]

Yeah, but driving it under 2,000 rpm all the time, makes the car "sleepy" in my opinion. I have had a lot of short trips and driving under 2,000 rpm for past few months and I got the feeling, that the car just isn't as it used to be, but I thought it was just me... After one longer trip with higher speeds (highway - 140-180 km/h), I noticed quite an improvement in the cars performance. It felt at least 15% better. I remembered that I got the same feeling every time I came back from a longer trip, which included a lot of highway driving. Not only with my car. So after that, I take it for a longer ride every now and then (highway, higher speed and rev's) just so it "cleans" from all that low-rev's-stuff-that-slows-the-engine 

I also did a "test". There's one part of the highway, where there's a speed camera. Before I reach the camera, I drive 140 km/h and after the camera, I accelerate.. Well sometimes I do, sometimes I don't. But..my point is, that I remembered that sometimes, when I accelerated, I reached max 190 km/h (according to speedometer) on certain distance (between the camera and some bridge). But after taking few longer trips and when I felt like the car really goes better, I did the same and I managed to reach 197 km/h (limiter) on the same distance or even earlier. And I did it few days in a row. The wetter conditions were very similar to those, when I could reach max 190-192 km/h.

P.S.: Please don't mind the speed, because after reading written above, you might think I'm a crazy driver or something, but I'm not. I'm just trying to explain the difference. And besides, sometimes, when going that fast, I still have to move to right lane to some even faster drivers.. Last day it was even a woman 

Okay, of course, there's possibility that ECU gets used to different (faster) driving and works different as when driving economically...

[unfamilia]

im on my first tank since i bought the car, still just above half a tank with 280kms... mostly heavy peak hour urban driving. 80kms of it was on the freeway only.
so looks like my estimates of 600km would be fairly accurate from a purely heavy urban commuter auto crdi.

i didnt fill the tank so im sure it wasnt filled to to brim when i picked it up to and was just off F. so will see when i do my first fill. seems to be lasting forever as i would have had to fill the forester by now for sure.

[Dazzler]

Sounds good... Petrol Stations are going to become unfamilia to you 

[Lakes]

Hi John.. Haven't tried to use cruise at a steady 90KPH (too slow) but at 100 or 110 I can drive more economically with cruise off (not sure if it would be the same in Trish's CW) but in the Hybrid cruise is more aggressive on the accelerator than I am 

Dazz you can't compair the Petrol 4 cylinder on Cruise as a lot less TQ so on hills they need to kick back a gear (if auto ) or throtle up to maintain speed, thats why i chose 1,900rev ( about 90kph ) as the CRDi is @ maxium TQ it holds speed up hills in 5th easy. V8 petrol's are much better than 6 cylinder petrol's on Cruise control as they will hold top gear, with 6's & 4's they need to kick back a gear on auto, if it's manual they just turn the CC off if they can't hold the speed you set in the gear your in. should be able to go faster @ 1,900 with a new 6 speed. but mate, drive that coast road 90kph is not borring in some parts thats got as many hill's and twists & turns as Tassie. a high Torque m @ low rev motor will get much better economy in hilly country than a low Torque at high rev motor. now tell me how careful you drove for economy on exter hwy? LOL ( thank's Trish wink  grin ) we all get the urge. but driving at 90kph not boreing if you have a goal to set.

[Lakes]

Hi Accim, just saw you think driving under 2,000 makes the car sleepy. i would agree if its heavy traffic, but on a trip of 4 hours the oil is warm and lubricating to perfection. Betsy is ready to fly after a run, might just be our warm climate? but once a week i give her a quick rev in excelleration just over 3,000rev to give the primary variable viens in the turbo some quick movement to stop them carboning up.

[Lakes]

My question is: for best economy in the diesel, is it better to keep the engine revving at around 1900rpm (the base of the torque plateau) or at lowest comfortable revs.


well depends on a few things like if your going up hill or down hill, if your in CC it will try to maintain the speed so if there is a lot of variations like, head wind or incline, the motor will have to trotle more @1,600 rev than 1,900rev as The torque just hold to speed easy less throtle. but like you said instant fuel useage would be good, but i think the economy gauge like the Ford Fiesta econetic use would be great. how many k's before your filling up with fuel? ( thats on a full to the top tank )

[neoto]

My question is: for best economy in the diesel, is it better to keep the engine revving at around 1900rpm (the base of the torque plateau) or at lowest comfortable revs.


well depends on a few things like if your going up hill or down hill, if your in CC it will try to maintain the speed so if there is a lot of variations like, head wind or incline, the motor will have to trotle more @1,600 rev than 1,900rev as The torque just hold to speed easy less throtle. but like you said instant fuel useage would be good, but i think the economy gauge like the Ford Fiesta econetic use would be great. how many k's before your filling up with fuel? ( thats on a full to the top tank )

My i30 had the instantaneous fuel economy display. Driving on a flat roat, I have a noticeable lower fuel consumption driving in higher gear at around 1500-1600 rpm than in lower gear at around 1800-1900 rpm. The 'shift now' display is doing it's job kinda well (except on the steep hills, where you really must ignore it).

The biggest improvement that I have been able to achieve in my driving, economy wise, is to always slip it into 5th as soon as it can cope.

My question is: for best economy in the diesel, is it better to keep the engine revving at around 1900rpm (the base of the torque plateau) or at lowest comfortable revs.

As tombodombo implies: The highest gear at the lowest revs gives the best economy as a basic rule of thumb.

[constipated]

As tombodombo implies: The highest gear at the lowest revs gives the best economy as a basic rule of thumb.

But how low should we go? 1500rpm? 1600rpm? Wouldn't it be great if there was a formula for any car you could work out the optimal speed/revs for each gear for best economy.

As tombodombo implies: The highest gear at the lowest revs gives the best economy as a basic rule of thumb.

But how low should we go? 1500rpm? 1600rpm?

You should go as low as you can but no lower.  Seriously, there is no actual number as it will vary by gear and terrain etc. It should be obvious when the engine is struggling.

Remember, we are just talking about economical driving. There are lots of other reasons to drive with greater revs and lower gears. Fun might be one.

[Torquey]

After almost 4 months & 6500 kms of Sydney city driving the display seems locked on 7.1 LPH in my auto. A bit of freeway driving drops this to 6.9 Cheers.

[beerman]

Was getting around 6.5l/100 in my CW auto, doing mainly highway k's with the cruise set to 120. lowering the cruise to 110k has seen a drop to 5.9l/100. The drop in revs for this speed drop is minimal just over 2500 to just under.

[Dazzler]

After almost 4 months & 6500 kms of Sydney city driving the display seems locked on 7.1 LPH in my auto. A bit of freeway driving drops this to 6.9 Cheers.

If you have done a few thousand kms of city driving the average would only drop very slowly when you start driving in the country. To get a true idea of your country economy you need to zero the readout first.

[unfamilia]

2nd tank of deisel and 580kms purely 100% urban, nothing over 80kmh.

7.4lt per 100kmh. And that's not til the light comes pn either. Im in love with this thing!

[Lakes]

This is with Crystal the 6 speed manual CRDi SLX i have 1,950k up & for the past two weeks i have only done Sydney  traffic trip Computer reading 4.9L /100k, on the trip i did two weeks back trip Computer read 4.5L /100k when i got home to sydney. on that trip weather was cold plus i had to do a lot of climbing crossing the Blue Mountains & the road surface out west is very rough so lot of rolling resistance. i think it's excerlent economy. one other thing i think you all should check regularly is tyre pressure. a lot of people neglect to check this, i'm runing 37 psi all round not sure if this is the ideal pressure but just thought i'd mention what i run. i think a few pound less in rear if your unloaded.

[beerman]

Down to 5.78/100. I think the ECU is getting used to my new driving style. Fuel light came on at 950k.....Would have gone for the thousand if I had somewhere to go. When I topped up I put in 55l.

For those who forget I have an Auto CW

[Dazzler]

That's awesome Beerman..

[beerman]

Good, but still shooting for better!!!

All things being equal, im thinking about some of those eco tyres to reduce it further.

Was getting around 6.5l/100 in my CW auto, doing mainly highway k's with the cruise set to 120. lowering the cruise to 110k has seen a drop to 5.9l/100. The drop in revs for this speed drop is minimal just over 2500 to just under.

I too have a cw auto, my experience is that 5.9l/100km is easy to achieve at 110kmh. If I drop back to 100kmh it will go down to 5.6-5.7. Pretty good I reckon   The car has done 16,000km and my fuel bill even with the inflated price of diesel is only 60% of what it was in a V6 Mitsubishi.

[Torquey]

After almost 4 months & 6500 kms of Sydney city driving the display seems locked on 7.1 LPH in my auto. A bit of freeway driving drops this to 6.9 Cheers.

Update @ 9000kms. 6.9 city & 6.8 with a bit of hilly freeway mixed in.