Lpg

What sort of mpg could you expect to get with an LPG conversion. Does it affect performance?

yes it does affect performance slightly, as for mpg it depends on your engine !

300tdi

You'll get roughly the same mpg at half the cost.

alanhid said:

300tdi

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thought the lpg kit you get for a diesel just gives it more performance ???

didnt think you got any more mpg, it defeats the object ?? as your using diesel and gas !!

I have looked into this in detail. I have a 2.5 petrol and once I finish my conversion I may lose 1 or 2 mpg, performance would be rougly the same but per litre it is roughly 60 - almost half the cost. If you have diesel it mixes lpg and diesel so that you are using less diesel. Thefore puts the cost of running down. For example you may be using 50% diesel and 50% lpg meaning that per litre of the mix you would be paying approx 85p. The mpg may go down by 1 or 2 but performance should stay roughly the same. Hope this helps!

Woah there - LPG cannot be used in the same manner on a diesel as a petrol without major and expensive mechanical mods.

On a petrol/lpg car, the driver can switch. The LPG can replace petrol as the main fuel.
Simples! On LPG, you use a bit more fuel for the mileage (it has a lower calorific value, so you need more litres to do the same work) Also, as it is used in Gas form, it takes up more space than the equivalent petrol would in the air/fuel mix, so you lose a bit of power through this loss of volumetric efficiency - typically 5-10% as a rough guess.
You can run more advance on LPG though, so you can claw back a little of the economy/power loss, but not all of it.
I have a 4.6 classic rangie - I get 18MPG petrol, 16MPG on LPG on the same run. Noticeably slower on LPG - but it's got oodles of grunt - so don't really notice.
You might notice on (say) a 2.25 petrol - would be good to try...
A useful by-product is that the LPG runs cleaner than petrol - so the plugs come out really clean after 12,000 miles, and the oil stays cleaner for longer...


Diesel/LPG cars run differently. They cannot run one or the other, without major expensive engine mods. They can run on diesel that is supplemented by LPG. This claims to improve the power (more fuel usually means more power) better MPG, but then if you are adding LPG, you would burn less diesel - I wonder how the overall MPG stacks up. And also improved combustion/emissions claims are made. I don't have first hand experience - so can't really comment on any of there - anyone out there with more info?