General Miles per Gallon

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General Miles per Gallon

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I was looking at my average mpg (for the motorway only) and I could only get 35 mpg. It is a 7 seater and there were 6 of us in it with a bit of luggage but it still seems quite poor. We went to the south of France last year and the Dobbie managed 40 mpg with a roofbox on.
Could it be down to the box section roofbars?
Without the box on, there's alot of wind noise, but I wouldn't have thought they could make that much difference.
 
It really depends, on my regular run to work I can get some days 65+ and other days only 35-40mpg on the motorway. Wind plays a big part on how far you have to put your right foot down to keep a constant speed, of which I've found 50-60 to be the best, or strangely 80... at 70 the MPG drops to around 30.
 
It really depends, on my regular run to work I can get some days 65+ and other days only 35-40mpg on the motorway. Wind plays a big part on how far you have to put your right foot down to keep a constant speed, of which I've found 50-60 to be the best, or strangely 80... at 70 the MPG drops to around 30.

That makes sense. In France we were cruising at 80 to 90 mph and getting better mpg. Over here you have to watch your speed a bit more cos of all the cameras and un-marked patrol cars.
I read somewhere that there's almost as many speed cameras in Britain as there is in the whole of the rest of Europe put together. France is particularly good. We only seemed to see one about every 100 miles, and they're well marked.
 
I find quite often in the Panda as well as the Doblo I get a higher mpg the faster I drive but that is only using the computer readout & not at the pumps.
 
I have just reached 2500 miles on my Dobbie 120. At first I was disapointed by my fuel consumption but it has improved as the engine loosens up. My overall consumtion is 42.1 I have carefully checked via the computer what it does at various speeds - on the motorway I get about 35mpg at 75. Around town with a gentle foot I get 46.5mpg. I have yet to try the 80+ option! I think it is all down to wind resistance, with that flat back the drag must be horrendous. Who is going to be the first dork to fit a spoiler? Great car though, would not change it. Thanks for all the Forum info - great site.
 
Actually that flat back helps the aerodynamics. The Doblo has a drag co-efficient of .30, which is good.
Funnily enough I have also discovered, after a five hour run at mostly between 80 and 100mph, that my mpg was excellent, seemingly 40+; better than at 70. However, there was little wind, and what there was was behind me. As Ozzie says, a headwind would have made a big difference. On another occasion I was powering into heavy oncoming rain for four hours, not going fast, and the mpg was terrible - mid 30s.

It all depends...
 
My mpg sounds about right then. Haven't looked an at average for town driving so I'll have to check that next. Being a Somerset carrot cruncher means there aren't many big towns, I'll have to check next time I'm in Bristol.
(there be tall buildings and lights at the side of the road up there)
 
Ulpian, your info very interesting. I really must try the fast option on my way to Scotland next week. Where did you get the drag coefficient for the Doble from?
Roger
 
Roger, I can't remember where I saw the drag coefficient stated. It was a very elaborate on-line article on the car some years ago, but if you Google up 'fiat doblo drag coefficient' you'll find various places where it's cited at 0.32. My memory must have been a bit out (not the first time), but that's still very good for a box.

Have fun with the drive to Scotland, and be careful. I don't carry roof stuff by the way, and I travel alone - with crud in the back!
 
I've been driving with the mpg thing on since last week monitoring my mpg. When I filled her up I got 64.5mpg at 35mph in 5th gear on the flat. :D Next day back to reality she was doing 47 to 49 mpg. I was doing 47.3 the other evening when I canned her up to 90mph and returned 47mpg - only a 0.3mpg drop - not bad eh?

My Doblo is a JTD SX cargo fully loaded. (y)
 
I did a bit of an experiment today on a 70 mile round trip. On the outward trip I kept up with traffic averaging 75-80mph and got a figure of about 45 from the computer. On the way back (with a bit of a headwind I think) I got about 35mpg at 80mph, about 46 at 70 and about 57 at 60. I wasn't being particularly scientific but reset the trip at each stage and drove as constantly as I could for about 10 miles. Some bits were more hilly than others, you can really see the mpg going down if you have to get up a steep hill but on average (going down as well as up) it was quite even.

I would be really interested to know how the mpg meter works, does anyone know?

DP ‘02 Doblo Cargo 1.9JTD
 
The onboard mpg display is not very accurate in my experience.

Mrs_G does approx 370-400 miles each day, mostly on motorways. She fills up at the same fuel station (Sainsburys) each evening and notes down the van mileage, trip mpg, and litres of diesel put into the tank to refill it. She resets the trip before driving off.

Doing a manual mpg calculation (miles since last fill/litres x 4.546) usually gives a result in the 45 to 50 mpg range. The displayed 'trip mpg' is always at least 5 mpg higher than actually achieved.

Trying to extrapolate mpg from short runs down the road is interesting but ultimatley prone to huge errors.

The only thing that the 'live' mpg reading could tell me that I'd be prepared to believe is that the figure drops the faster you go. Having said that the displayed figure could vary quite wildly. My car (V70 2.4T) has a 'fly by wire' throttle and cruise control. If I set the cruise control and watch the 'live' mpg display it is amazing how it varies while the car stays at the same speed. Obviously hills and inclines have an effect but so do other vehicles nearby, variations in wind direction etc. My point being the figures given by the standard onboard mpg calculators are to be taken with a huge pinch of salt.

To get a good average mpg for your vehicle, for your type of use, there can be no real substitute other than using the vehicle, keeping good records of fuel used and miles covered and doing the maths.

In my line of business its not unusual to hear drivers of commercial vehicles talking of how good/bad their vehicle is regarding fuel usage. When questioned it is not unusual to find that in reality they don't have a clue what they are talking about. They will quite often say something along the lines of 'I filled up at A, did 3 deliveries in B, went over to C and then came back here and it still shows more than half a tankful on the fuel gauge'. One guy was doing some sort of calculation based on a gallon being 4 litres!!! No wonder he throught his 3.5 ton Sprinter gave over 40mpg fully loaded at 70mph. At that point I usually go and find someeone with more than 2 brain cells to talk to.
 
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Mrs_G does approx 370-400 miles each day, mostly on motorways.

Wow, she must really love driving! or her she must *really* love her Doblo!!

To get a good average mpg for your vehicle, for your type of use, there can be no real substitute other than using the vehicle, keeping good records of fuel used and miles covered and doing the maths.

Ah but it's so much more fun watching the little mpg display going up and down. Actually on a slightly more serious note, I realise the thing must have a fairly large margin of error and that it's probably a bit optimistic as well but it is quite a useful tool in showing you what style of driving works best for mpg and what average speed to go for your own best balance of fuel consumption, speed and comfort. Personally I find I'm happiest (most relaxed, least road noise, good enough progress in our over congested roads etc) at about 70. DP
 
I must admit some people think the Doblo does no more than 50...

That's what I do on the M4 on my way to work. I get there just as quick doing 50 than leaving 10min later and do 75+ due to traffic build up.

I generally average about 60-65mpg doing 50mph... but at 90+ (where legal :eek:) I still get about 35mpg :rolleyes:
 
traffic conditions notwithstanding I think I'd find it hard to stick to 50 (it was much easier in my old Transit) the JTD is such a willing engine you almost have to drive with no right foot at all to stay under 70. And what's really nice is that you're well under 3000rpm - it's brilliant!

For anyone's information (e.g. if you're thinking of getting one) the Doblo with the JTD engine is a great vehicle. Before getting the Doblo, I drove around for 3 weeks in a brand new Nissan Primastar. Now that's an excellent van but at about £15K it's way out of my reach. My 'new' Doblo is an 02 with 75K on the clock, one owner with full history and cost just £2.2K and it's the best small van I've driven (which includes Kangoo 1.5DCi, Combo 1.7DTi and Berlingo HDi). I'm trying hard not to be too gushy but I can honestly say that I'm as happy driving the Doblo as the Primastar. DP
 
Wow, she must really love driving! or her she must *really* love her Doblo!!

I just like to have her busy earning her keep. Mind you she sometimes objects to cooking my diner when she gets in at 10pm after doing her 'little run oop north'. :devil:
 
1.3 multijet 2005.
Generally disappointed with mpg particularly above 60mph. My old montego would return 65mpg at 60mph but this only gives about 57mpg . however, It is good round town at 56mpg .
Someone said that consumption was better with the 1.9 - but all the mpg numbers in these posts are even worse than mine.
towing a caravan brings it down to about 30mpg - despite other people's views this is not a bad experience provided that you are happy with 55mph. Caravan =1100kg gross .
Would the new 105 1.9 engine be more economical as someone suggested?
 
Figures on fiat from the trip computer which seems ok to me. Figures on montego from fill up tank method.
 
I used to own a pug pickup with a 2.3 diesel engine.
On the motorway I would average 50+mpg as long as I kept my speedo under 55. As soon as I cranked the speed above this you could see the needle move.

Having only recently bought my dobbie I have no idea what the mpg will be. I ran it 'till the fuel light came on then filled the tank right up - 47 litres - and zeroed the trip counter.
When the yellow light comes on again I'll have some figures for town driving - but I'm already ahead on my last car, having done 170 miles & still not hit the halfway marker.
 
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