What Mpg Are You Really Getting?

[Graeme C]

Been keeping a track of how much petrol my Aygo has been using (I know it's a bit sad but I'm stopping now!)

When I first started using the car was getting around 54 mpg over the first 500 miles, was reasonable happy with that.

Just racked up 2000 miles and checked - now getting 64 mpg!

I thought I'd lost a receipt from a garage so even went through my debit/credit card statements to double check I hadn't.

I don't flog the behind off the car and tend to do short commutes and 26 mile back and foward to work a day via the A1 (more urban than A road!), drive smoothly and rarely go above 65 mph (not as bad as a sunday driver like)

Filled up with Shell V Power all the time, except from my first two tanks. Engine seems perkier and smoother - but that could be my imagination or the car running in.

Can't understand how consumption seems to vary for others - I just think my Aygo's great - the great fuel consumption makes it even better!

[BadBoyVTEC]

mines crap. from a full tank now im often seeing a total of 230 miles with 2 bars left.

[daveyjp]

Now had chance to check twice. Car has done 1900 miles. From warning 'bong' I put in 15 litres and managed 162 miles before it bonged again = 49 mpg this was over Easter when we did lots of running around.

Put in 20 litres after this and it's just bonged again on 187 miles - 42.2 mpg. These journeys have consisted of rush hour traffic, plenty of stop start - 30 minutes to do 7 miles and 100 miles of 70-80mph motorway work. Aircon always on.

[matty_aygo]

i relli need to start driving more echonomical, mine always seems to have the bars flashing. i never fill it up to the top thou, usally put a tenner in max and get about 130/140 miles that average?

[Jan van de Wouw]

On average I get just above 50mpg and can't seem

to get it worse than 42mpg, no matter how I try :P

Best yet is 54mpg and my car's done just

under 7500mi since I bought it last september.

[kenl]

The only way to get an accurate answer is to go from fill to fill. Fill the tank until the gun clicks off, ideally do this a few times and take an average.

I've not been driving the Aygo much recently but when I was driving it along the motorway I was getting 59mpg.

[Unklian]

My second tank full gave me....

45mpg.

This was at "running in" type revs on a light throttle

with mainly about 20 mile trips often with air-con on. Not the best useage for economy

but i dread to think what some of my big cars would have done treated in this way.

Rover P5B auto, Opel Senator auto, Rover SD1 3.5 auto, Cavalier V6 auto, All about 18mpg genuine I think.

The car is still running in but in a few weeks, I'm off to Scotland.

I'm going to see what the Aygo will do at a constant 70mph for a few hundred miles.

(It is uphill all the way though :D )

I'll average it out with the downhill trip to England.

Ian.

[Graeme C]

I got my car with a full tank of petrol and 10 miles on the clock.

I have added all of the petrol used since delivery to take it back to a full tank - I fill it to the click every time anyway. So maybe Ken has a point - isn't the digital guage and 'beeping' a bit tempremntal anyway.

As an aside I find I seldom use fifth for any length of time (except runing downhill!), preferring to drop to fourth as soon as the speed drops.

Don't know whether using 'premium' fuels makes any difference either, or maybe it's the colour of the car.....

[ytareh]

As the guy who started this thread and having reviewed the posts so far Id say its fair to conclude that for the average 'open road' driver who doesnt get stuck in traffic 52mpg is the best guess average.This is a fair bit shy of the official 'extra urban' average.In many cases in the past I have found that cars return BETTER mpg than the official figure so this is a bit disappointing for a car most will buy for reasons of economy....Still its a respectable average just not brilliant...I cant imagine running anything else however, especially here in Ireland when a Yaris/Micra etc is a third dearer to buy...

[PeterK]

As the guy who started this thread and having reviewed the posts so far Id say its fair to conclude that for the average 'open road' driver who doesnt get stuck in traffic 52mpg is the best guess average.This is a fair bit shy of the official 'extra urban' average.In many cases in the past I have found that cars return BETTER mpg than the official figure so this is a bit disappointing for a car most will buy for reasons of economy....Still its a respectable average just not brilliant...I cant imagine running anything else however, especially here in Ireland when a Yaris/Micra etc is a third dearer to buy...

[PeterK]

I have filled my Aygo twice since I bought it. The first fill-to-fill gave me 57.5 mpg, the second 60.47 mpg

Both were a very similar mix of road types, about 10% urban (but no traffic jams), 40% motorway and 50% country roads. These figures appear to show an improvement as the engine beds in.

I find it easier than in my last car to keep inside the speed limits. The nice big 30, 50 and 70 mph markings on the speedo are easy to see and the car seems to be 'happier' at the right speed. In my old car the speed was always creeping up and up and I was having to brake a lot to check it.

[daveyjp]

"In my old car the speed was always creeping up and up and I was having to brake a lot to check it."

This is due to incorrect gear selection, not the car. If the car is driving you drop a cog and remain in control. I've found in hilly Yorkshire 3rd is required in the Aygo in 30 zones otherwise the car drives me even on slight downhill sections.

[Arise2]

I don't know your metric system but...

The oficial paper said 5.5 liters for 100km. (5.5%)

And I'm geting always over 7% (7.5% is usual). The highest I got was 8.3%.

I drive only in the city.

[Jan van de Wouw]

I don't know your metric system but...

The UK isn't metric, it's "Imperial"...

while allmost all of Europe uses "liters per 100kilometers" or "kilometers per liter" the British use Miles per Gallon (MPG)

One mile is 1,609344km and one Imperial Gallon (as there's also a US gallon) is 4,54609 liters

I'm geting always over 7% (7.5% is usual). The highest I got was 8.3%.

7l/100km translates to 14,3km/l and 8,3l/km is equal to 12,0km/l and those numbers

translate to 40,3544195 MPG and 34,0338478 MPG which is quite bad in my opinion.

[adilmon]

D4D aygo averaging 70 mpg driven normally

[Jan van de Wouw]

Is the Diesel in an Aygo a D4D?

As I understood the D4D-technology was developed by Toyota,

but the Diesel Engine in the Triplets is a 1.4 HDi by Peugeot...

[frovin]

Petrol:

I drive like a 90 year old. But even so, this is what i get for milage...

46 mpg on avarage. Highest ever is 48 (motorway driving on a sunny day). Lowest ever is 37 (congested city driving during winther). My car has done 6000 miles.

Here is how i drive:

When i hit 2000 rpm, i shift. Whenever is see a stop ahear, I use the engine break. I try to use 5th gear as much as possible, even at speeds as low as 35 mph.

I am really trying to squeze as much as possible out of the car (for the enviornment, for my economy and for my satisfaction), but I cannot get nowhere nere what other ppl are doing.

Tips and tricks about how to increase the efficiancy are very welcome.....

Jakob

[daveyjp]

Frovin - from reading the threads this doesn't seem out of the ordinary and tallies with figures we get -mid 40s in urban traffic with the occasional high speed dash.

I have just managed 50 mpg from the last 30 litres, this included some longer runs over the weekend on quieter A roads.

[kaffe-koko]

Petrol:

I drive like a 90 year old. But even so, this is what i get for milage...

46 mpg on avarage. Highest ever is 48 (motorway driving on a sunny day). Lowest ever is 37 (congested city driving during winther). My car has done 6000 miles.

Here is how i drive:

When i hit 2000 rpm, i shift. Whenever is see a stop ahear, I use the engine break. I try to use 5th gear as much as possible, even at speeds as low as 35 mph.

I am really trying to squeze as much as possible out of the car (for the enviornment, for my economy and for my satisfaction), but I cannot get nowhere nere what other ppl are doing.

Tips and tricks about how to increase the efficiancy are very welcome.....

Jakob

You gear up too yearly. The engine isn´t burning fuel very effective then. You accelerate during a long period of time. Accelerate fast (3000-4000rpm) at second or third gear to the desired speed,. Then speed is reached .. use the accelerator smooth. More fuel is used during a much shorter time. Overall this is much more effective.

Fuel consumption depending on the throttleposition, not gear. To accelerate in 5th gear at low speed requires more fuel than using the third ie. Full throttle in 5th gear 2000rpm uses as much fuel as full throttle at 3th gear in 6000rpm.

[zerosome]

Fuel consumption depending on the throttleposition, not gear. To accelerate in 5th gear at low speed requires more fuel than using the third ie. Full throttle in 5th gear 2000rpm uses as much fuel as full throttle at 3th gear in 6000rpm.

I'm not an automotive engineer nor a technician, but this doesn't sound entirely correct to me. There is no doubt that fuel consumption is dependent on throttle position, but I'm also inclined to think it's dependent on engine RPM. As far as I know, the fuel-air ratio is not dependent on RPM or throttle position, so the fuel consumption should always be proportional to the air consumption (i.e. - having a linear relationship). As the amount of air consumed is proportional to the frequency with which the cylinders are firing, it seems pretty clear that fuel consumption must increase with engine RPM.

[sullsims]

I'd say its probabley best to change gear at 3 000 rpm

[zerosome]

I'm not an automotive engineer nor a technician, but this doesn't sound entirely correct to me. There is no doubt that fuel consumption is dependent on throttle position, but I'm also inclined to think it's dependent on engine RPM. As far as I know, the fuel-air ratio is not dependent on RPM or throttle position, so the fuel consumption should always be proportional to the air consumption (i.e. - having a linear relationship). As the amount of air consumed is proportional to the frequency with which the cylinders are firing, it seems pretty clear that fuel consumption must increase with engine RPM.

Having written all the above, I decided to do some quick research to avoid making a fool of myself. Here is what I've found:

Fuel Mass = Engine Mass Airflow / Stoichiometric Ratio

Where,

Engine Mass Airflow = RPM x (Manifold Air Pressure / Absolute Temperature)

These equations appear to exclude any factor for throttle control, but I would assume that it's simply a scalar along these lines:

Engine Mass Airflow = Throttle Position x RPM x (Manifold Air Pressure / Absolute Temperature)

I'm still trying to understand the exact relationship between engine RPM, throttle position, gearing, velocity and fuel efficiency. At wide open throttle, it's pretty straight forward. With a variable throttle, it becomes much more complicated and I'd really love to have a conversation with an automotive engineer that could explain it to me.

But in the end, I think your best bet will be to try and find some balance between keeping your RPM and throttle position as low as possible. And of course, the conventional wisdom is that you're better off accelerating slowly rather than quickly (though I don't think this is a given, since the slower you accelerate, the longer it takes to reach your desired velocity, so I need to sit down and do the math at some point).

That being said, I believe the key is anticipation: the less braking you do, the less energy you're wasting. It's always preferable to coast to a stop rather than using your brakes and it's even better to never stop at all.

[Jan van de Wouw]

It's always preferable to coast to a stop

When you DO coast, leave the car in gear and doe NOT depress the clutch.

That way there is ZERO fuel consumption at that moment!

At least with Electronic Fuel Injection (which the Aygo has)

Very simple: the car has speed and mass, the mass wants to keep its speed

so it "drives" the engine through the wheels, differential and gearbox.

When this happens it's the mass that's keeping the engine rotating,

so if you let go of the throttle the crank-position sensor "sees" the engine

is making enough revs not to stall, so it completely cuts off the injectors.

If you depress the clutch the drive from the moving mass of the car is gone,

so the engine speed drops and when it drops below a certain point the ECU

starts putting in fuel again to keep the engine from stalling.

That's why it's best to "brake on the engine" and coast in gear...

[Laura G]

I haven't worked out the mpg so far but only done ~800 miles! In the latest fill up (from 2/6 bars) I squeezed in £32 but that is probably a reflection on UK petrol prices rather than the size of the tank...

After a journey of 150 miles there were 5/6 bars left, now after 185 miles 4/6 bars left. But I'm suspicious of 'disappearing bars' too, will see whether there are still 4/6 bars left in the morning! ;)

As for when I change gear, my Black has no rev counter... so change when it sounds right

[Jan van de Wouw]

There's a list of speeds in certain gears and when to change up.

I believe it's 30mph from 3rd to 4th and 45mph from 4th to 5th

for shifting at 2500rpm, but I'm not 100% sure as I drive metric :P