High mileage in a E39 540i Touring LPG

[matt21]

...am I mad?

I will be doing 25,000 per year. I currently drive a 525i so get 30mpg. Reducing costs is a benefit but not bothered about super economy want something I can enjoy.

I am guessing circa 25mpg long distance commuting giving an equivilant of over 50mpg. Whats the catch? Why arent more using LPG?

540s seem to be going for less than 523i 528i and even if I put the conversion on myself would only come out about the same as a 530d.

Looking at a 1998 model with all the bits for circa £2500.

Finally apart from fuel do 540i's cost much more to run that say a 528i

Thanks

[Vixpy1]

Remember that LPG is less efficiant, you will get far fewer mpg on it.

E39 530d would be my choice.

[matt21]

I thought that the good kits would be nearly as efficient as on petrol??

[clonmult]

I think that whilst LPG has a higher octane rating, it has a lower calorific value (or something like that), which means you maybe get 10% worse mileage.

[welwynnick]

I think you have the right idea, as long as the car suits you. The 540i doesn't have such good steering and handling as the 6-cyl cars, but I didn't find my E39 540i/6 manual was expensive to run. It was quite heavy on tyres, but I usually got 30 mpg commuting and 35 mpg cruising. LPG may give a bit less. Assuming the octane rating is higher, if you use lpg most of the time (quite likely) the engine management should be able to advance the ignition and get some of the efficiency back.

Nick

[matt21]

forgetting fuel costs for a sec will a 540 cost much more to run than a 528. ie are things like brakes much more, are they less reliable, do they require special oil just general day to day costs??

[welwynnick]

matt21 said:

forgetting fuel costs for a sec will a 540 cost much more to run than a 528. ie are things like brakes much more, are they less reliable, do they require special oil just general day to day costs??

The 540i doesn't feel as nimble as smaller engined cars, and is more at home on big, long, open roads, and is almost uniquely talented as a long distance cruiser. My neighbour used to have an E39 528i, and we compared notes. I don't think mine was significantly more expensive to run in any respect. Yes, runnig costs are slightly higher, but considering the performance advantage, I think it's inconsequential. The engine sump has greater capacity, so oil changes cost more. The brakes are bigger than the 528i (though same as the 530i I think) so pads and discs cost a bit more. 540i's usually come with larger wheels and tyres, but then many 6-cylinder cars have them as well. Clutches on manual cars don't always last very long. Those are all considerations, but I don't think they are enough to have any impact on a buying decision if it's the right sort of car for you. BTW, the 535i seems to have most of the disadvantages of the 540i, but with few of the advantages. Dont forget the cost of converting a V8 to LPG will be slightly higher than for a 6, but again that's not a big deal.

regards, Nick

[agent006]

Vixpy1 said:

Remember that LPG is less efficiant, you will get far fewer mpg on it.

The better set up the LPG system is, the less gap there will be between the two fuels. Given your line of work, I assume this would be obvious to you.
The problem comes when people just bung a condenser ring onto a V8 and leave it at that.