[Euro] Fuel Consumption

it seems impossible to get 9L/100km in city areas..like no long distance driving i mean....mine does about 11L/100km i think. When measuring does it matter if you decide to refuel every time you get to half way? coz i feel that first 200kms or so is good with fuel then it gets to be more....or maybe i just rev it a bit...i dont really...on ocassions i go to 3000RPM - 4000RPM...i try not to.

In regards to not fueling up when its almost empty...i can see what you mean when you say dirt builds up at the bottom...so its good to fuel up when you have around 10L remaining...but doesnt the petrol get sucked out of the tank from the bottom anyways?

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Originally Posted by way2quik

it seems impossible to get 9L/100km in city areas..like no long distance driving i mean....mine does about 11L/100km i think. When measuring does it matter if you decide to refuel every time you get to half way? coz i feel that first 200kms or so is good with fuel then it gets to be more....or maybe i just rev it a bit...i dont really...on ocassions i go to 3000RPM - 4000RPM...i try not to.

In regards to not fueling up when its almost empty...i can see what you mean when you say dirt builds up at the bottom...so its good to fuel up when you have around 10L remaining...but doesnt the petrol get sucked out of the tank from the bottom anyways?

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If you're doing 100% stop start traffic (i.e. traffic jams and traffic lights), and drive an auto, then it will be difficult to get 9L/100km. For me, I shift at 3000rpm in 1st, 2500rpm in 2nd, 2000rpm in 3rd to 5th. It's a very low shift point, because it's just too busy here to accelerate quick. But I drive this way when I am in the city/suburbs, and when I get out to less populated areas, I can give it a full throttle to redline about once every day or 2 days and still get 9.5L/100km. The car is very efficient if you apply light throttle to maintain speed, because it has EGR to reduce fuel consumption. And when going downhill, leave the car in gear and don't press the accelerator. This closes the throttle while keeping the engine spinning.

yeah but i dont use the triptronic feature. So i dont know when it shifts. But i just ALWAYS try not to go over 2500RPM now. Well this is what im goinna do from now on. That will surely reduce fuel right? what is EGR? i was also wondering like say you drive at 80KM/hr and a traffic light comes up so you gotta go to zero. Is it better to just apply breaks and let the automatic downshift to every gear until zero stop OR is it better to put it on neutral and let it slow down to zero without changing gears?
I know its weird to do this on an auto but i thought it would be better.

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Originally Posted by way2quik

it seems impossible to get 9L/100km in city areas..like no long distance driving i mean....mine does about 11L/100km i think. When measuring does it matter if you decide to refuel every time you get to half way? coz i feel that first 200kms or so is good with fuel then it gets to be more....or maybe i just rev it a bit...i dont really...on ocassions i go to 3000RPM - 4000RPM...i try not to.

In regards to not fueling up when its almost empty...i can see what you mean when you say dirt builds up at the bottom...so its good to fuel up when you have around 10L remaining...but doesnt the petrol get sucked out of the tank from the bottom anyways?

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way2quick

The figures I have posted on the previous page are based on a 55 k commute each way, of which approx 30k are running on the freeway, against the traffic, i.e. basically 100 kph constant speed. Another 10 k is as at 80kph with a few stops and the balance is typical suburban. Manual transmission helps.

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Originally Posted by way2quik

yeah but i dont use the triptronic feature. So i dont know when it shifts. But i just ALWAYS try not to go over 2500RPM now. Well this is what im goinna do from now on. That will surely reduce fuel right? what is EGR? i was also wondering like say you drive at 80KM/hr and a traffic light comes up so you gotta go to zero. Is it better to just apply breaks and let the automatic downshift to every gear until zero stop OR is it better to put it on neutral and let it slow down to zero without changing gears?
I know its weird to do this on an auto but i thought it would be better.

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My figures are more realistic, since I live in the Eastern Suburbs of Sydney, drive through the city (with the damn traffic jams once in a while), go through the tunnel and out at Willoughby, up past Chatswood to the Northern suburbs. So my driving is city driving with 50 and 60 speed limits, while the Tunnel and the short stretch after that to Willoughby is limited to 80km/h. I'd claim that my driving is 70% city and 30% on the tunnel/freeway, without exceeding 80km/h (unless I want to lose my license).

EGR is where part of the exhaust gas is recirculated into the intake, so you have some exhaust gas (not combustible) and some fresh air. Since fuel is only needed to be injected based on the amount of fresh air, the exhaust gas will become a filler, and thus you use less petrol, only the fraction required for the fresh air. The EGR system only activates at light throttle with low load. So it is easier to drive with it with a manual rather than an auto. But basically, if you keep your foot only lightly on the accelerator so you can maintain speed or even accelerate slowly, you'll save lots of fuel. This is probably the reason why the Euro is able to return fuel consumption figures similar to the official figures, while for other cars they usually return an extra 1L/100km higher in real life.

When you are slowing down, DON'T put it to neutral. Even a driving school will tell you that. It's for safety, in case you need to accelerate to avoid an accident. But also, when slowing down and leaving it in gear, the ECU will shut the injectors, letting the engine spin using the momentum of your car, thus saving A LOT of fuel.

Just use your brakes normally. Let the auto transmission downshift itself, in D. There is no point is purposely engaging a low gear to engine brake. You'll just wear your transmission a bit more, and saving the brakes is not really worth the potential auto gearbox wear.

A lot of the fuel consumption figures are amazing. Most likely wouldn't be able to pull it off with an AT. But then again, it's possible to get good fuel economy just by taking it easy. IE, don't plant your accelerator too heavily at the lights, taking your foot off the accelerator earlier when you see red light ahead, etc.

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Originally Posted by nexace

A lot of the fuel consumption figures are amazing. Most likely wouldn't be able to pull it off with an AT. But then again, it's possible to get good fuel economy just by taking it easy. IE, don't plant your accelerator too heavily at the lights, taking your foot off the accelerator earlier when you see red light ahead, etc.

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Yeah, here are my top tips to save fuel:
1) If you don't need to accelerate quickly off at a traffic lights, use LIGHT throttle and shift at 3000rpm in 1st, 2500 in 2nd, 2000 in 3rd, 4th and fifth. Don't use MEDIUM or HEAVY throttle and shift at 3000rpm in 1st, as that is just a waste of fuel It is not the rpm that consumes petrol, but the amount of throttle you give.

2) When you are going downhill, even a gentle down slope, use 5th gear (or 6th if it is downhill at 80km/h and above) and release the throttle. This closes the injectors, while still letting your speed stay roughly at that point.

3) When slowing down, DON'T shift to neutral or press the clutch. This not only takes away your opportunity to accelerate in an emergency, but also forces your engine to spray the injectors to maintain idle speed rather than fully close and rely on momentum to spin yoru engine.

4) When maintaining speed, use the ideal gear to keep at 2000-2500rpm with VERY light throttle. This activates the Exhaust Gas Recirculation (EGR) system and saves you fuel.

5) Other tips recommended such as driving closely behind another vehicle to cut through the wind and using neutral downhill do not save enough fuel to offset the additional risks you put yourself in. So it's not recommended to do those.

I can't stay below 4K rpm :D That's why my fuel consumption is like 14L/100km or so, haha! I had 3/4 tank initially, and how a little under 1/4 of a tank, and I've done around 270km or so. Not to mention each of my trip is less than 20 mins of driving.

excellent tips aaronng, learnt a few new things :)

Oh yeah, regarding tip #1, notice the revs are very low in 3rd, 4th and 5th gears? It's between 1500-2000rpm there, so you must not press the accelerator too hard! Otherwise you'll lug the engine. With light throttle, the car will accelerate, but with heavier you'll feel the engine vibrating more as there is more engine load but not enough revs.

But usually when i slow down to zero from 80 at traffic...i watch the rev meter...and lets say it stays at 1100 rpm...at 60 when i slow down to lets say 40 the revs will go up to 1300rpm or something...then go back down...and so forth when you slow down even more..so from that i see that its downshifting constantly till u hit zero.

iumm just ignore what i just said, i understand what your saying now about momentum of car.