LPG

Get the V8, get the V8...........

Sensible head back on...Welcome to the forum. 

The 740i will be a thirsty beast but it's a V8, did I mention that before?. The 728i gets a good write up in terms of being the best 7er to buy as once you start getting upwards in the engine displacement department the fuel costs outweigh the joys.

It would make sense converting a big older car into a LPG muncher, the boot would be big enough to take a reasonable tank, but it will cost anywhere between £1,000 and £2,000 to get a good conversion done. 

Will you actually get this back in terms of the saving in fuel?  That is the real sums that you need to do.  Will you keep the car long enough to make a saving?

LPG is about £0.70 a litre, unleaded for me is about £1.29. a litre so thats about a 45% saving straight away but an engine run on LPG isn't as economical as an engine burning unleaded, so you need to take that into consideration.  There are a number of LPG converting companies that now advertise on the TV, you've got nothing to loose by giving them a call.

If you live anywhere near me (Renfrewshire) you will struggle to actually find a petrol station that actually sells the piggin' gas.  And you may mind you end up running it on unleaded!

There has been discussions on here about LPG conversion but I don't know if anyone has actually done it.  I've looked into it but it just doesn't stack up for me as I can't buy the stuff in my local area where my car spends 99% of its crusing time.

Andrew

Ahhh, right that changes things a bit.  I don't have a feel for the mpg figures but there might not be much in it in terms of cost to run per mile then and it's then down to preference.

I would look at what mileage is on the 740i and what toys are on it and what toys still work compared to what's on the available 728is

I have run 730s and 728s on LPG for the last 16 years with no problems. The mileage is around 25 to 27 overall with up to 32 on a run in the UK, and more on the Autobahn. I do about 20K miles a year. Compared to petrol, the performance is up a little, (1 second a lap at Croft last time I measured it).

Cost of a good conversion for a 6 cylinder engine is not less than £1700, and probably more for the 8 cylinder. By Good, I mean one that uses the ecu of the car, and has an injector for every cylinder. Do not buy a system that has less injectors than cylinders, as they tend to blow up your inlet manifold or airbox when there is a back fire.

As to obtaining gas, I tour Scotland regularly and have never had a problem finding gas.
Visit http://www.lpgmap.co.uk/ for a list of gas suppliers, and download them all into your satnav Use a TOM TOM - the BMW one probably will not have points of interest. I stick my Tom Tom on the screen of the BMW sat nav in my current 2001 728i.

If I am down on gas, I just tell Tom Tom to take me to the nearest station. Usually upwards of 20 stations within 50 miles or so. In the North of Scotland there are not so many, but Oban and Aberdeen always have LPG, and there are more every year.

Its worth deviating up to 20 miles off route rather than running on petrol - especially in Scotland. LPG near me costs from £0.685 a litre and petrol from 132 for 3 star.