Fuel consumption at highway speed LLams

[NavyDiver]

LLams had a side effect for me while at high speed you might like to consider if you have it. Link

I wonder how low the fuel use would have been if i had removed my roof rack, did not have 200 odd litres of fuel, took the A.T.R. off and put road tires on and tried this LLams lowering at speed trick
Not having a full load of 7 people in the car might help a little I guess but where is the fun in that.

[101RRS]

I run on the road at onroad height and -20 in LLAMS and have not noticed any difference in fuel consumption and I record every drop consumed.

Garry

[SuperMono]

Many things can make a difference.

I don't have LLAMS or adjustable height as my D3 has those old fashioned metal coil things at each corner.

On a recent trip up to Woodend the overall consumption was 7.4L/100km.
It was sitting at about 9 on the way up, then the run home the distance to empty just kept rising as the rising tailwind pushed us along.
Much of the return trip (at 100-110kph) was down in the low 5L/100km range.

I have noticed a difference of around 1-2L/100km between road tyres and M/T.

I haven't tried driving a complete trip in manual mode and picking up 6th more often, over a short run this seems worthwhile.

With a 1400kg full height van behind I run around 14-17L/100km depending on conditions.

If my wife drives the consumption is about 2L/100km higher than me.

So many variables, so little opportunity to determine what works best.

[NavyDiver]

I run on the road at onroad height and -20 in LLAMS and have not noticed any difference in fuel consumption and I record every drop consumed.

Garry

My test was not a perfect test given the hills and fluctuating gradient and strong winds Garry. Playing was interesting and the difference was a noticeable 2 litres per hundred kilometres. I changed several times and reset the fuel usage monitor each time. I did not find any difference twice and did find a difference 3 times. Not a boffin just playing.
My long range tank has no gauge so I am still blissfully unaware how much more is in it before I get to the main tank.

[Tombie]

I run on the road at onroad height and -20 in LLAMS and have not noticed any difference in fuel consumption and I record every drop consumed.

Garry

Garry, perhaps you can answer this one for me...

It seems many moons ago, all blokes recorded their MPG...
I always put it down to lower wages, tighter living costs of the 50s 60s 70s etc.. and perhaps a diagnostic tool for out of adjustment carbies...

But it seems many still - to this day, log their fuel consumption.

In a business scenario, where it can all be claimed, and is a cost I can understand..

But why in a private vehicle?

When I drive, I fuel the vehicle up.... Whens its low, I fill it up again...

Consumption has no effect on my driving - I drive because Im going somewhere, if I use 5 litres or 500 litres doesnt matter.

So why does the practice continue to this day? And with fuel pumps being so poorly calibrated, Temperature / volume fluctuations etc... How can one be certain? And when odometer inaccuracy is taken into account, plus rolling diameter changes due to tyre wear... Well accurate is impossible.

[101RRS]

But why in a private vehicle?

When I drive, I fuel the vehicle up.... Whens its low, I fill it up again...

In Jan 94 I took delivery of a new 3.9 Interim Update D1 and as it was my first V8 I started to record fuel consumption to see where I could make it more economical. I sold that D1 3 months later and got one of the very first D1 Updates - again a V8 - it had much worse consumption than the earlier V8 but could be surprisingly economical if you wanted it to be.

Got into the habit and just kept doing it - takes a second to record in a little book. I have found issues in the vehicle by monitoring fuel consumption. In the 101 - ignition issues had it down to 35l/100km and when fixed back at 20l/100km.

So habit more than anything - however I just record fill up amounts and when I am the car waiting for someone - I work out the actual consumption for a my entries - passes the time while waiting.

Garry

[Stuart02]

why does the practice continue to this day? And with fuel pumps being so poorly calibrated, Temperature / volume fluctuations etc... How can one be certain? And when odometer inaccuracy is taken into account, plus rolling diameter changes due to tyre wear... Well accurate is impossible.

Inaccuracy is ok so long as its a consistent bias, which mostly they are, and things like tyre wear are gradual.
I definitely learnt a lot about my car from keeping an eye on fuel use - its how I picked up on my leaking D2 fuel pressure regulator.
Really useful for long trip planning, and understanding tyre pattern and pressure effects, roof-racks and trailers...
Plus my Dad always did it so of course I do!