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Discussion Starter #1
Hello everyone!

I bought an Alfa Romeo Giulietta 2.0 JTDM-2 140 PS last month.
It is a 2011 model year and my first Alfa ever!

For now i love the car so much, but i have once concern.
The gas mileage is horrible and way off the advertised 5.7l in the City.
My main commute to work is a 6km long drive, uphill in the morning and downhill in the evening, but there is absolutley no traffic and almost no stop lights.
I even roll down hill in neutral. Other drives are to the city, also not much traffic and i drive very careful generally. (sometimes i do enjoy the car, but that is not in the calculation)
Yet after everything, my average fuel consumption is almost 9L per 100km.
I think this is way off and im thinking if something is wrong with the car that i should check.

Any ways to improve it or someone who has similar issues?

Thanks!
 

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I believe the answer lies in how you are using the vehicle. 6 km. really isn't far enough to get the engine into its efficiency envelope. I monitor the consumption on mine and even on the level the first 2 miles/3.2 km. it is nowhere near that for similar distances and terrain later in a journey. Uphill and then down hill does not balance out, again I've tried assessing the comparative consumption and it isn't a case of 'swings and roundabouts'. Also coasting in neutral does not improve consumption, actually it is counter-productive as in neutral the engine still has a load placed on it, whereas in gear on the over-run the load on the engine reduces to zero, I've taken the readings that show that the consumption changes along with slight changes in accelerator position and incline.
Do some longer journeys, monitor the actual consumption on the display and see what I mean.
 

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Discussion Starter #3
I believe the answer lies in how you are using the vehicle. 6 km. really isn't far enough to get the engine into its efficiency envelope. I monitor the consumption on mine and even on the level the first 2 miles/3.2 km. it is nowhere near that for similar distances and terrain later in a journey. Uphill and then down hill does not balance out, again I've tried assessing the comparative consumption and it isn't a case of 'swings and roundabouts'. Also coasting in neutral does not improve consumption, actually it is counter-productive as in neutral the engine still has a load placed on it, whereas in gear on the over-run the load on the engine reduces to zero, I've taken the readings that show that the consumption changes along with slight changes in accelerator position and incline.
Do some longer journeys, monitor the actual consumption on the display and see what I mean.
sounds reasonable. i will do that then and then judge if something is wrong with the car.
Also are you sure it is better to go downhill in gear? how can it be that the consumption is better then?
I also thought im placing strain on the engine in that case.

Thanks!
 

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Some fuel systems on deceleration will cut the fuel almost completely, whereas coasting in neutral the engine is just idling and will be fuelled accordingly.

It’s also not very safe to coast downhill in neutral as you have less control and will have to use the brakes more, which can overheat them and almost might increase wear, so what is saved in fuel is lost in more frequent brake rebuilds. Maybe.
 

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I drive a 10km commute to work in my 2.0JTDM. After three months i'm just under 15km/1l. It was not the consumption I calculated with but I guess the trip is just to short...
 

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I get nowhere close to the rated motorway consumption in anything but the most perfect conditions on my 170MA. Wouldn't say it's bad on MPG, but with 80% motorway driving I'm averaging about 7.5-8L / 100km. Obivously a bit lower instantanous when going on flat motorways @ about 100-110km/h, where I'm usually seeing around 6L/100km, which is decent.
As previous posters have said, coasting in neutral wastes more gas than coasting in gear as the fuel won't cut out.
 

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Some fuel systems on deceleration will cut the fuel almost completely, whereas coasting in neutral the engine is just idling and will be fuelled accordingly.

It’s also not very safe to coast downhill in neutral as you have less control and will have to use the brakes more, which can overheat them and almost might increase wear, so what is saved in fuel is lost in more frequent brake rebuilds. Maybe.
The second paragraph is spot on. My brother, as an experiment, tried coasting downhill in neutral and scared himself ****less as a result of the lack of control. Needless to say he didn't repeat the experience!

It's all here:-

https://www.lightfoot.co.uk/news/2018/02/02/bad-technique-coast-driving-downhill/
 

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The worst we have ever had on ours, that includes short trips and hard driving is 39mpg (7.25L/100km)
In mixed driving we average around 46mpg (6.1L/100km) and on a steady run 55mpg (5.1L/100km)

I would say you have something wrong. I would start by checking easy stuff, like brakes (make sure they are not binding), check the coolant is getting up to temperature.

I have found with ours that on cold days if you have the heater blowing fast it really makes the engine take longer to warm up. In fact when driving slowly the heater causes the coolant temperature to drop.

That will also increase fuel consumption a lot. Also winter/poorer quality fuel will cause a reduction in fuel economy.
 

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I get an average of 49mpg from my 170 diesel, which is 5.8l/100km. My regular commute is a 50:50 mix of motorway/dual carriageway and town driving, and start-stop is its usual unpredictable self.

On long motorway runs I’ve got almost 60mpg on one occasion (4.7l/100km), but I mostly expect around 50mpg. The instant figure is so variable I pay little attention to it, but around town it can be as low as 30mpg (9.4l/100km). Obviously that means the engine is warmed up properly.

Short runs on a cold engine will never give anywhere near the quoted consumption figures. I’d take it for a long run and see how it does, but the advice to check for binding brakes etc is good. Easy enough to check with a jack that the wheel spins freely.
 

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On my 170 diesel's board computer it averages 5,8l/100km, but actually it's 6,3l/100km. Checked it by calculating, so BC actually lies about 0,5l.
 

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Even if coasting did reduce fuel consumption it shouldn’t be done as you’re not in control of the car under those conditions. Also, I believe that the alternator has the intelligence to generate when you lift off the throttle.
 

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Mine takes a little bit of distance to sort itself out. If you're only driving 6km each way to work then, as others have said, you're not really giving the car the chance to warm up and it's therefore not being as efficient as it could be.

My fuel consumption increases quite a bit for the first few miles, and then drops again once the car has warmed up.

Not sure whether it's been mentioned above (have to admit that I didn't read all of the replies!), but if you're only driving short distances then your car might be trying to carry out a DPF regen. This increases the fuel consumption quite a bit while it's going on, although you will usually notice that this is happening because the exhaust note changes, and the car becomes a little less responsive.

Take it for a good blast up the motorway if you have one near you. Sit at 70mph for a few miles (about 10-12 minutes) in 4th gear so that the car is doing around 3,000 revs. This will get the exhaust and DPF really hot and should clear out any soot which would have built up by driving short distances.

The DPF needs heat to clear itself out properly. If you don't provide that heat, then it doesn't clear out. The soot will build up in the DPF and this in turn causes the car to be less efficient and can cause real problems if you don't clear it out from time to time. Short distance driving doesn't provide the required heat.

For reference, my G is a 2.0 JTDM with a Stage 1 remap. My long term average for the last 1,000 miles (according to the trip computer) is 59.1mpg, or 3.98l / 100km..!

My DPF tends to need a regen every couple of weeks as most of my driving is short distances too.. Luckily I have a motorway between where I work and where I live, so I just take a different route home every now and again to clear it out!
 

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“you're only driving short distances then your car might be trying to carry out a DPF regen. This increases the fuel consumption quite a bit”

And the irony is the extra mileage taken to get the regen!
The plasterer who doing some work at our house says some vans now have a button to bring on a regen so you can blast the stuff out under your control!
 

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“you're only driving short distances then your car might be trying to carry out a DPF regen. This increases the fuel consumption quite a bit”

And the irony is the extra mileage taken to get the regen!
The plasterer who doing some work at our house says some vans now have a button to bring on a regen so you can blast the stuff out under your control!
:lol: I wish my G had that. Mind you, I've got into a bit of a routine now where I take it for a blast up the M5 every week or so on my way home, which should mean that it doesn't want to perform a DPF regen quite so often..
 

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I drive 17000 miles a year and therefore diesel makes financial sense. I can get 60mpg and on my commute if I drive slow and 55mpg if I drive normally.
On a 6km commute the diesel engine is going to spend hardly any time running efficiently.

Sent from my BBB100-2 using Tapatalk
 

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Discussion Starter #16
Mine takes a little bit of distance to sort itself out. If you're only driving 6km each way to work then, as others have said, you're not really giving the car the chance to warm up and it's therefore not being as efficient as it could be.

My fuel consumption increases quite a bit for the first few miles, and then drops again once the car has warmed up.
Well yea, it does run old most of the way, it reaches the otpimal temp only in the last 1km of commute

The DPF needs heat to clear itself out properly. If you don't provide that heat, then it doesn't clear out. The soot will build up in the DPF and this in turn causes the car to be less efficient and can cause real problems if you don't clear it out from time to time. Short distance driving doesn't provide the required heat.

For reference, my G is a 2.0 JTDM with a Stage 1 remap. My long term average for the last 1,000 miles (according to the trip computer) is 59.1mpg, or 3.98l / 100km..!
Wow, those are some incredible numbers haha.
I will see to do a DPF clean out on the highway and check to see the brakes this month if they are locking maybe.
Thanks!
 

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Totally different kettle of fish by my cloverleaf gets 37mpg with a sprited drive of 7 miles followed by queuing for a further 7 miles into work. And then a nice fun drive on empty roads to get home later.

So 37mpg is pretty decent I would say.

but I would seriously swap to a petrol if that is the kind of regular mileage you are going to be doing.
 

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I've recently acquired a 2012 2l Veloce with the TCT box and the economy isn't what i expected either. I do a mix of short journeys during the week but then the car gets a couple of longer runs at the weekend, typically 60 or 70 miles. I'm averaging about 38/39 mpg. On a recent 70 mile journey it only achieved 42mpg. I came from a 18mpg Porsche previously so the mpg is awesome but nowhere near the stated figures for the car. The car has only done 69k miles and has a full history so seems looked after. Doing the same journeys my 159 2.4 diesel would return around 34mpg with about 46 on the longer journey. The previous owner only done 3000 miles in the last year which were possibly short journeys so perhaps i need to take it for a blast and force a regen? I remember my 159 doing a regen on its own but it only happened the once.
 

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TCT figures always seemed deceptive. There was a mega-disgruntled guy a few years ago who lived in London and couldn’t accept the economy he was getting but obviously that was with only short urban trips. At least you get some space in the footwell!
 

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I only do 4000 miles a year and learnt to my cost that a diesel wasnt good for this amount of mileage . Luckily it wasnt an alfa but a Vauxhall Signum. It killed my DPF because it never got a chance to regen properly.
 
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