LPG users - real world mpg or miles per £?

Mmmm here is my history

1999 converted my then 130K mile Alfa 155 with mixer ystem, cost £1250. petrol MPG 33, lpg 26 mpg. was troublesome to start with till I fpound someone who knew WTF he was doing to set it up properly, ran fine after that. mLPG at that time was 30p/litre,(petrol ~ 85ppl IIRC)

next up , Saab 9000 2 litre non turbo, fuel strangely identical to the alfa 9 33 petrol, 25/6 lpg), basic mixer system cost 1K to do. absolutely no issues with it at all in > 70K miles, fleabayed in teh end and got 850 quid for it which I was gob smacked at

next on V70 2.5 LPT, blew the budget with a 1500 quid Prins sequential gas injection system. never used it on petrol but it did a good 21-23 mpg sat at fast motorway speeds and never to gentle with the right foot. covered 90K in that car, again ZERO issues with teh LPG system ( water pump packed up and took head gasket with it but that would have gone equally on Petrol.

Current car

Audi A8 V8 4.2 quattro Sport, bought already converted but with a Prins system that I got checked by my local boys before buying. I'm keepinga close record of fuel on this as we have a recording system on an A8 site I frequent.

Fast motorway/B road messing brings 17-18mpg, taking it very easy and sticking to a max 75 returns > 21 mpg ( i reckon clear traffic and good cold damp mornings I could break teh 23 mpg barrier but I'd be bored to tears I must admit)

I'm currently paying 53-56p/litre so working on petrol at 106 I'm getting 34-36 mpg driving quickly in a 300bhp V8 luxo barge. in contrast, driving my wifes Co Astra 1.9 TDI auto in a similar manner gives me 35 mpg........


so, boring rep mobile or quality V8 barge....

You decide

[quote=wpo750]1997 Jeep Cherokee 4.0l which I bought with a single point system already installed. It has a supposed 70 litre tank into which I can only ever squeeze 52 litres which at 51p/l costs £26.52 to brim.(/quote]

You can only fill the tank to 80% of its capacity, because LPG expands! So a 70 litre tank can only take 56 litres max.

Subaru also offered a factory-approved conversion on some models.

I converted an 2002 facelift e46 330i and it was great.

The major drawback was the small 45l tank I fitted and if I do it again I will get a bigger tank and sacrifice boot space or getter a bigger car like a 5 series. That 80l tank sounds great - any links to that car?

In my opinion LPG is best done on powerful engines so you get to be smug about your fuels costs and enjoy a decent engine. My 330i was costing the same in fuels as 320d so I felt very smug indeed. The power drop on LPG was not noticeable on an engine like that unless you really looked for it.

Reliability/issues none really apart from initial set-up and teething issues:- in the beginning we had issues with the car stalling when in slow traffic as the Prins kit's ECU didn't have as good a anti-stall system as the Bosch ECU that is standard with the car (when you run on LPG you use the kits ECU and when on petrol you use the cars ECU - that is my understanding of how it works but I may be wrong). When I say anti-stall I mean the ability to put the car in 1st or 2nd and then let the clutch out gently and without using the throttle the car creeps forward and does not stall. On LPG it wouldn't do this as easily - it needed some fine tuning and was better but never as good as when on petrol - not a major gripe though and I learnt how to drive around it easily enough.

Hard driving and LPG: I used to drive a vtech Honda before the 330i and drove the 330 much the same way. I had a 'moment' once when negotiating a long, sweeping motorway offramp (M25 to M3 clockwise if anyone knows it). I was on LPG and the level of gas was very was low. Negotiating the bend caused the gas to go to one side and gave a 'empty' reading. This results in a beep and an automatic switchover to petrol. Of course throttle is momentarily cut as the switchover happens so resulted in a bit of tail wag.
The engine warning light came on after that so I took it back to the LPG fitter who read the ECU and then asked me what exactly I was doing at the time as it showed the throttle was wide open and at high revs(!) when the switchover happened causing the ECU to register a fault. Fault cleared and all ok since then. Since then I made sure that if going for a blast that the LPG level was goo or I would fill up with some high octane petrol and run on that instead just for kicks. The throttle response and torque/power at high revs was slightly better on petrol although it would do an indicated 150mph on both fuels..

Economy: The cars OBC told me my average on petrol was 25mg which tied up with my tank to tank tests on petrol. On LPG I was getting 21mpg (tank to tank check). It only used petrol for a short time upon start up - negligible amount - some people talk of it using lots of petrol if you do many short trips - not on mine though - perhaps a rubbish system.

IMO use a good, experienced fitter with the best kit available that has been used on other cars like yours - most of the complaints you see on the net about LPG seem to originate from poor kits or bad installation to cars that are already in bad shape or unreliable before the kit was fitted.

You cannot take it on the channel tunnel. But you can take it on the ferry, you just need to let them know of this in advance. I drove to auchen hypermarket in france with my dad, family and relatives. me in the fiesta, and him in his E-class converted into LPG.