Bongo Fury

I`ve had my 2.5d 2wd for about two years now and have been getting about 28-29 mpg using it for commuting, shopping trips etc. I have just refueled having returned from my first trip which involved a fare bit of motorway driving,
and I can`t believe it, I returned a figure of 37.5 mpg.
I kept it around 60mph and between 2200-2400 revs. If I could only duplicate this for the rest of the year.

Having said that the 2wd was rubbish at getting into a muddy camping field, had to park in the pub car park.
A well c`est la vie

Malc

malc_s wrote:I`ve had my 2.5d 2wd for about two years now and have been getting about 28-29 mpg using it for commuting, shopping trips etc. I have just refueled having returned from my first trip which involved a fare bit of motorway driving,
and I can`t believe it, I returned a figure of 37.5 mpg.
I kept it around 60mph and between 2200-2400 revs. If I could only duplicate this for the rest of the year.

Having said that the 2wd was rubbish at getting into a muddy camping field, had to park in the pub car park.
A well c`est la vie

Malc

That does sound truly remarkable, but maybe not impossible. A following wind helps (seriously!) and flat terrain also. Regarding muddy fields, I found likewise with my 2WD. I keep some Fiamma grip strips aboard at all times as (some) insurance against things getting really bad. If it wasn't for this seriously awful wet weather though (which could stuff even 4WDs at times I think), I think my 2WD would cope OK with my general camping needs, and it is an easier and more economical proposition to own, overall, so musn't grumble. You can't have it all ways, sadly.

Is that proper briming the tank method, or just lucky guess? . My personal best was 33 mpg which I was quite happy / surprised with.

I`ve just double checked my figures.

241.3 miles, filling tank to brim took 29.25 litres (not even half a tank) = 37.5 mpg.

The road was pretty flat, and I don`t reckon I overtook anything.

I did tail gate a lorrry ( not to close) for a few miles which might have helped.

malc

malc_s wrote:I did tail gate a lorrry ( not to close) for a few miles which might have helped.

malc

that would help considerably, just so unrelaxing to have to be on the ball for braking.

I'd love to do a sum on the value of a following wind. Given that air resistance rises as the square of the speed through the air, then the value of a following wind should rise in similar proportion the more you reduce your groundspeed whilst having a wind behind you. If that wind is even moderate (say 15 mph) then reducing from - say - 70mph to 60 mph means a reduction in airspeed from 55 mph to 45mph which is an 18% reduction, whereas in zero wind the airspeed reduction would be only 14%. The air resistance would do down as the square of the difference. In addition, I'll bet the Bongo's best fuel metering is below 2250rpm and with only a light 'dwell' on the throttle pedal. But still, 37mpg is very impressive. I assume you filled tank from brim to brim, and that your wheel rolling radius puts your odometer at 100% accurate (e.g. does your Satnav report that your speedo is giving an accurate reading?).

run that pass me one more time

malc

malc_s wrote:run that pass me one more time

malc

I thought it'd make you laugh

Regarding getting a bit of assistance by following lorries, I wonder what the optimum distance is for a given speed?

If you look at the way hedgerows and tree branches sway as lorries pass by, the delay is often quite considerable and the maximum turbulence is not always, as one would imagine, immediately behind the vehicle.

The question is: Where is the zone of maximum suction in relation to obvious turbulence?

Are some drivers skilled enough to feel the assistance?

If so, would you feel it more in a larger or a smaller vehicle?

Frank

I seem to remember some guy years ago setting a speed record on a push bike by riding behind a Jag with a vertical plate fixed on it, something like 120mph I think.

However, setting records is one thing, personally I reckon it's an accident waiting to happen following a lorry to get a pull.
I'm not sure it even works that well. Judging by the spray that lorries kick up if there was an area of low pressure behind then the spray would follow the lorry.

Hi
I reckon the results are a bit skewed, as "Brimming the tank" can get different results on different days...REALLY.Personally, I check the figures over more than a dozen fills, and try to fill the tank at the same time of day to account for the temperature differences in the day over here, and I have always scored between 29 and 32 MPG....usual figure being 29/30....and I'm very happy with that when weighing up MPG to usefulness of vehicle factor. Considering that many of the minis I owned in the '60s / 70's didn't do much more, I can't see why there's anything to complain about the Bongo fuel useage
Cheers
Helen

malc_s wrote:
I did tail gate a lorry ( not to close) for a few miles which might have helped.

malc

this would of helped mpg loads, i used to do it in my T4, I also do triathlons and even swimming and cycling the if you are in the draft of someone else you use at least 75% effort of what you usually use

in Ironman Triathlon you are not allowed to cycle within 10Metres of the following bike as it is said to cause an unfair draft advantage so if you imagine that advantage with a bloke on a bike, think about the draft zone of a lorry! it must be massive

i still draft lorry's i think 10-15 meters behind one should help out a bit (and hopefully give you enough time to swerve out the way if something happens) and you can feel it as you go in and out of the draft zone ....give it try (at own risk ) your revs will drop for the same output of speed

Hanksy wrote:

malc_s wrote: i still draft lorry's i think 10-15 meters behind one should help out a bit (and hopefully give you enough time to swerve out the way if something happens) and you can feel it as you go in and out of the draft zone ....give it try (at own risk ) your revs will drop for the same output of speed

10-15m behind, you can't possibly see what is likely to be happening in front of that lorry. If he had a blowout you would be right in the path. Like I said, an accident waiting to happen.

briwy wrote:

Hanksy wrote:

malc_s wrote: i still draft lorry's i think 10-15 meters behind one should help out a bit (and hopefully give you enough time to swerve out the way if something happens) and you can feel it as you go in and out of the draft zone ....give it try (at own risk ) your revs will drop for the same output of speed

10-15m behind, you can't possibly see what is likely to be happening in front of that lorry. If he had a blowout you would be right in the path. Like I said, an accident waiting to happen.

yep i know but it saves £2 on fuel

briwy wrote:

Hanksy wrote:

malc_s wrote: i still draft lorry's i think 10-15 meters behind one should help out a bit (and hopefully give you enough time to swerve out the way if something happens) and you can feel it as you go in and out of the draft zone ....give it try (at own risk ) your revs will drop for the same output of speed

10-15m behind, you can't possibly see what is likely to be happening in front of that lorry. If he had a blowout you would be right in the path. Like I said, an accident waiting to happen.

There is a brutal, uncomfortable but convenient truth about all this though. By the conservation of momentum, a truck going into the back of a car will not come to as abrupt a halt as a car going into the back of a truck.

...i'll fetch me coat

P.S. the Tour de France commentators did say 80% of cyclists effort was pushing air out of the way. It is why Bongo back boxes make more sense than roof racks.

Hi malc_s,

Are you using sunflower oil,if so it might be the Flower Power that is giving you this Great mpg.

Great result