cooltide said:

I would expect at least 150 miles from 60 litres on short runs, around 180 miles on longer runs

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Which means the real-world MPG average is 11.37, covering 150 miles using 13.20 gallons of fuel
(60 litres as you said) and on
180 miles the real-world MPG average is 13.64, covering 180 miles using 13.20 gallons of fuel
Now if I am not mistaken is thsi a low MPG on LPG because normally Land Rover and many people said that the average MPG
Running costs
Urban MPG: 12.6 mpg
Extra Urban MPG: 23.1 mpg
Average MPG: 17.7 mpg
CO2 emissions: 376 g/km (As you recommended I will go to the MOT station and get the exhaust gas analyzed)
What kind of Land Rover or Range Rover are you driving?

cooltide said:

I could get 180 miles on a single point system with lambda control out of 58 litres on a rover 4.6 v8.

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I suppose I am right by saying that your engine is NOT supercharged so if mine was 4.2 and SUPERCHARGED would the MPG be the same, does this make sense to you?
I mean this might be because mine is supercharged?

cooltide said:

There will be scope for your installer to fine tune

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What does this mean and what does it do?

cooltide thanks for replying to all my questions, I really appreciate that. Thanks
I had low MPG problems even before I converted my car to LPG but I didnt realise until someone told me that it is very low MPG,
so I decided to convert my car to LPG which was clearly no help at all. Besides RR website say that the average is
Urban mpg: 12.6 mpg and lets say my engine is old (64k mile) it is about 10/11 MPG
Average mpg: 17.7 mpg and lets say my engine is old (64k mile) it is about 14/15 MPG
Extra Urban mpg: 23.1 mpg and lets say my engine is old (64k mile) it is about 20/21 MPG
So I want to find out the people who are driving range rovers the same age as mine
(4.2 supercharged jag engine) what is there MPG?
And what shall I do step by step (test something, do I diagnostic test, oxygen senser, air filter etc)?
My ECU tells me if there is a problem on the dashboard but it isnt so I am sure there is nothing?
BUT maybe it doesnt say about the spark plug or any other things?
Just basically tell me what to do, I would appreciate it.

Rover v8 in a range rover classic. Much older engine design than jag. i worked out i achieved 15mpg petrol, 13 mpg lpg depending on use.

Awad said:

What does this mean and what does it do?

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LPG ECU will have a fuel map and read sensor information just like your petrol efi ecu. It may still be "learning" so a tank or two is worth burning before jumping to conclusions or exhaust analytics, if it feels like it is running well

cooltide said:

i worked out i achieved 15mpg petrol, 13 mpg lpg depending on use.

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Why is your petrol MPG more than your LPG?
I thought they burn the same amount of fuel...
For example whan I spend £110 petrol it will be £55 LPG

LPG has a lower calorific value / slower flame front than petrol and an octane around Ron 110+
In order to optimise its use, you need a good spark igniting the cylinder charge slightly earlier than with petrol.
It is always less efficient but much cheaper and cleaner burning than petrol.