Running a small petrol car vs Running a big car, on gas..

[Zelandeth]

I've zip experience with LPG, but my former flatmate had a thing for Jags, so I've lived alongside XJ's of each iteration from mid 80s to around 2000.

 

They're universally lovely to drive when working well.

 

They are however bloody complicated cars, and can be frustrating to work on, parts tend towards the expensive side of reasonable, and the online enthusiast community generally seem to be the type who are more concerned about the fact that you haven't polished the chrome cap on the windscreen washer jets than answering the basic nuts and bolts question you asked.

 

The IRS setup on the early 90s cars at least was an absolute swine to sort out on the one car, and I reckon we must have replaced every damn bush on the back of the car - and it still bloody clonked sometimes. I also hope never to have to change another cabin heater circulator water pump ever again. Yes, the heater has its own water pump. On the late 90s XJ8, it tries to occupy the same physical space as the nearside exhaust manifold, which is where most of the skin from my knuckles and wrist still resides.

 

They're made to be driven and to be thrown at a well equipped garage by an owner with deep pockets.

 

I still regret not buying the green one...but at the same time I know how big the bills my mate paid just in parts and I know how many hours we both spent on them...it would have both bankrupted me and driven me insane.

 

I'm not saying don't do it, but just make sure you're going in eyes open. Buy the absolute best car you can too, none of these cars like sitting around, so have a look at MOT histories and keep that in mind if it's clearly only been out for the occasional Sunday and to the testing station... that's not necessarily a good thing.

[Guest Hooli]

I believe most of the power loss on LPG can be regained by advancing the ignition as it burns slower than petrol.

[Rod/b]

We had a Prinz / Keihin multipoint converted Kia Sportage. It was great for about 30k miles until it burnt the valves and the head had to be replaced. Turns out it should have had the flashlube kit fitted but Prins forgot to add the Kia 2.0 engine to the flashlube list...

[DaveDorson]

Won't be buying a big Jag for a while if at all now.  I've decided to buy a sensible* daily driver in the form of a TDCI Mondeo Mk3 (ST) Estate.

 

Project thread on this forum..

[Lanciaman]

I run a 2006 Subaru Outback 3.0 on lpg. Prins V2 system I believe it is. Bought it already installed.  Its now on 117k miles but no idea when it was converted.  The Outback is a thirsty bugger at the best of times, and according to the no doubt optimistic fuel computer I've done 28mpg over the past 5k miles.  Only time I really measured it was on a long run on the Mway when it got around 26 mpg on LPG. Not great. But given LPG at the fill was 53p a litre, the actual cost is fine. Overall on normal running on my 7 mile rural commute, all bendy roads and hills, I guess it is doing the equvalent of around 38 mpg petrol cost.   For that we have a 3.0 4wd auto with 245 bhp max output.  No turbo to wrong, no dual mass flywheel to go wrong, no dpf to clog up.  Sure geting LPG can be a hassle as a few round here have closed down the past years, but still available with a bit of planning - and it does still run on petrol if needs be.   I'm all for the big engine LPG rather than puny petrol.   Bear in mind the big engined cars, often autos, are so much more within engineering tolerances and less stressed , its a no brainer.

[lisbon_road]

Don't forget that there is also the option of a small or smallish car on gas.  I run a Mk3 Astra on gas and get 40 mpg on gas.  Running costs are low, starts and runs on gas so oil stays clean for ever.  Plus you can be real self righteous about emissions.  

 

Our local garage has also closed for lpg, so it isn't as convenient as it was.  But I still recommend.

[chodweaver]

Long time owner of a Chrysler Grand Voyager with LPG on the GM 3.3 V6, converted by an owner prior to the one that sold it to us. LPG only became a problem as a result of coolant loss through HGF - the highest part of the coolant circuit is the pipes feeding the vaporiser - this would become airlocked, the vaporiser would freeze and the LPG would stop flowing, forcing a switch back to petrol. The conversion was not particularly tidy, but functioned very well. I don't think it caused the HGF. Usable capacity of the doughnut tank in the bootfloor was 66l, giving a range of about 220 miles on LPG alone. Always started on pez with auto switch to LPG once warm. Slightly less mpg on LPG than on petrol, but apparently no less power (not that the V6 outputs oodles anyway - the state of tune is very low). Makes for a very nice way to eat up motorway miles in luxury though and at half the fuel cost.

 

Ime, the price of converted vehicles isn't increased by having LPG - it may even put some buyers off. Of the two converted vehicles we've bought (both Voyagers), I don't think either had paid back the owners that converted them - they hadn't done enough miles - so my advice is buy converted rather than coughing for a conversion yourself. But do be picky about the way it runs on LPG and how the fit of the kit looks, then get the LPG kit serviced by someone who fits and services lots of them. The second Voyager we bought had the splicing into the injector loom done right by the injectors on the fuel rail and then insulated with cheap electrical tape, that had gone brittle and given up after time and high temperatures, leading to lots of running and electrical problems and error codes. Time consuming to put right, but not difficult.

 

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[GeordieInExile]

What I've never understood is... Given LPG is such a cheap fuel, why isn't it more widespread? Why don't manufacturers offer it as a fuelling option as standard?

[catsinthewelder]

The Prins list of cars not suitable for LPG includes most stuff from 2006 and includes lots of Jaguar Land Rover products and, surprisingly, Mercedes.

I was driving this a few days ago.

 

 

It's a bioethanol powered Sprinter. The chap who owned it (and the white one behind) deals in gas powered vans and had booked us for a removal with our van which wasn't big enough to carry everything. With lots of delicate things on board I didn't really test the available power but it was fully loaded and made it up steep hills without complaint.

[Lacquer Peel]

What I've never understood is... Given LPG is such a cheap fuel, why isn't it more widespread? Why don't manufacturers offer it as a fuelling option as standard?

It was fairly popular in the late 90s/early 00s. My uncle for example was an LPG evangelist back then, but when his LPG Espace expired he bought a diesel Multipla instead.

I think one issue for him was chasing LPG filling stations.

[hennabm]

The dvla give me a “massive” discount of £10 per year for having lpg fitted.

So even taking the installation cost at only £1200, that’s only 120 years before I break even.

 

But it does mean until April next year I can drive into Londinium free from Ken’s surcharge.

After April the ULEZ affects it and is no longer exempt,

[Bfg]

What I've never understood is... Given LPG is such a cheap fuel, why isn't it more widespread? Why don't manufacturers offer it as a fuelling option as standard?

 

^ that comes down to the costs involved in putting vehicles through full type-approval, for what has proven to be a very limited market. This cost is multiplied by the numbers of countries a vehicle has to be approved in.  Even though most countries have reciprocal agreements with other nations and trade / economic communities - each and every LPG tank and its installation, together with each vehicle's very specific crash protection approvals would have to go through a veritable Himalayas of legal paperwork and test-to-destruction facilities. 

 

Without a better fuel-station infrastructure in most countries, the manufacturer would have to provide dual fuel vehicles. And duplicate systems equals more complexity, warranties, servicing, build cost and weight in their cars.  Extra weight = lesser performance.  More things going wrong, and higher cost with lesser performance is neither liked by the marketing chaps, the press, or the public. 

 

For many years now, the option of LPG has been provided by outside companies, and their success*  has been rather limited.  Motor manufacturers look at these figures as indicative of the returns they might expect if they offered LPG on their cars ..and the figures don't add up to profit. 

 

Furthermore, most cars simply don't have the necessary space for dual fuel tanks. Those cylindrical or donut shapes don't actually tuck-in very well. Remember also that fuel tanks now have to be sealed from / external to the passenger compartment, and this rules out any and all vehicles without a boot or too low a ground clearance to sling the tank underneath.

 

Dual fuel engines are a compromise - because any engine is designed / optimized for a particular type and grade of fuel. This works best with a certain compression ratio, engine speed, ignition and valve timing, fuel injection system, bore to stroke ratio, engine speed, and combustion chamber shape.   An engine specifically designed for LPG might easily be very much more efficient - if each of these factors were altered.  But switching fuels is a compromise, and whichever fuel the engine is not best set up for - the motoring press would just love to slag off.   

 

And God knows - if LPG vehicles were to become more popular then don't you think the government would simply raise the tax. ! ?

 

Bfg

[Lacquer Peel]

There were factory LPG vehicles from Proton, Volvo, Vauxhall, Ford and maybe others at one point.

[Bfg]

.

^ Undoubtedly there were others too, but as they are no longer - might just confirm that they were more trouble than they were worth &/or not as profitable.  At one time fuel tanks were fitted inside cars (like the Triumph Spitfire) with a piece of hardboard between the petrol tank and the occupants.  Legislation has changed a lot since then.  

[DodgeRover]

Ford, Vauxhall, Volvo and Rover all offered factory fit lpg vehicles as an option in the UK.

 

Have seen loads of small engined vehicles converted driving school minis and Micras for example, I did spot someone filling a smart car at one time! Breakeven time is obviously longer unless you are doing high miles in a smaller engined vehicle.

[andy18s]

What I've never understood is... Given LPG is such a cheap fuel, why isn't it more widespread? Why don't manufacturers offer it as a fuelling option as standard?

It's far more valuable being sold for home heating so the pumps get what's left.....

[Bfg]

There were factory LPG vehicles from Proton, Volvo, Vauxhall, Ford and maybe others at one point.

 

 

Ford, Vauxhall, Volvo and Rover all offered factory fit lpg vehicles as an option in the UK.

 

 

^ Interesting Thanks.  Mind you I've not seen a single car advert saying "original / factory fitted LPG" so I guess they were either very expensive or else a well kept secret.  From the manufacturer's point of view ; add on kits do help limit their legislation and liability obligations, to those markets they know are easiest to deal with.  However as an ex-motor-industry professional - I'm rather surprised any kits were 'factory fitted'.  I would have thought at best they might have been an 'authorized' or possibly a 'dealer supplied option'.  Still I'm always pleased to learn. 

 

Must admit I still like LPG and when I'm looking for the next car - it'll be high on my priority to check out LPG car adverts again. 

[omegod]

I had a 3.0 V6 Omega that was allegedly factory fit LPG, in reality the option was ticked and once built an LPG kit was bunged in the back of the car at the factory, the supplying dealer then sourced a local installation, VX supplied a NECAM kit which can be a right pain in the arse when they go wrong allegedly. I put 30k on it and it ran rough at one point so I took it back for a service to the installer who remembered fitting the kit 10 yrs previous. It worked out great in terms of running cost at around 22 mpg round town and 38 on a run , LPG was 47p a litre at that time 

 

 

I'd like a Lexus LS400 if I can find a decent one on gas

[lisbon_road]

Perhaps I'll be a bit more specific on my experience.

 

I ran my Sierra on lpg for years.  This was an open loop system but worked ok.  Moved from a carb based system to a fuel injection manifold on my two litre pinto, which gave a huge increase in power.  I also had another Sierra with an open loop system which worked well on a two litre twin cam.

 

I now have a mk3 Astra with a Polish sequential injection system.  This starts on gas and runs very well and smoothly and has given no problems.  It was installed by competent Poles.  In Southampton, we've now lost our only major LPG Shell station as a risk assessment said that there wasn't enough room around the tank so it had to go.  Great.  Other cities seem to have more.  My impression is that conversions are now rare, and the areas where LPG might survive a bit longer are those where local authorities allow lpg taxis.

 

The Astra starts on gas, which you're not supposed to do as the system has to guess the injector settings and when cold, a gas can be a long way out.  This to my mind forgets the fact that escaping propane is more benign that escaping petrol.

 

These new systems using liquid injection sound really good, but I do wonder how many conversions are being done.  As society moves away from anyone doing anything to their cars, so such stuff gets rarer.

 

My wife's car is a Vauxhall Zafira A with a BRC system.  Doesn't start on gas but runs smoothly and I have no complaints.

 

I'd really (really) appreciate the views of anyone who really knows what is going on in this industry and what we should expect.

[DodgeRover]

The installer I know says he is as busy as ever, he does a lot of older large engined vehicles which people intend to run till they drop.

I met a Bulgarian refueling a foreign registered RHD Honda, he had brought it here and driven it home to be converted, an injection system cost either £400 or £600, it's the labour costs that increase the price here as it's a multi day job, nobody can do a quality install quickly.

[lisbon_road]

Pleased to hear it DodgeRover, not my impression but I'd much rather you are right not me.

[Guest Hooli]

^ Interesting Thanks.  Mind you I've not seen a single car advert saying "original / factory fitted LPG" so I guess they were either very expensive or else a well kept secret.  From the manufacturer's point of view ; add on kits do help limit their legislation and liability obligations, to those markets they know are easiest to deal with.  However as an ex-motor-industry professional - I'm rather surprised any kits were 'factory fitted'.  I would have thought at best they might have been an 'authorized' or possibly a 'dealer supplied option'.  Still I'm always pleased to learn. 

 

Must admit I still like LPG and when I'm looking for the next car - it'll be high on my priority to check out LPG car adverts again. 

 

When I worked for a ovloV dealer around 2000 S/V40s did occasionally turn up on the transporter with dual fueling all working from the factory.

[hughwbarrie]

A couple years ago when I was commuting from Bournemouth to Kent twice a week. I bought an elderly S-type that had been converted twice previously.

 

It started life with a BRC kit and then about 18 months prior to my purchase it was re-converted with a Stag kit.

 

On the run to kent I was getting 25mpg which was an equivilent of 50mpg when you took into account fuel costs 60p lpg vs 120p petrol, always felt better on lpg too.

 

Was a complete bargain for £750 with a years mot too.

 

Did me good for a couple of years. Only sold due to moving to a rural location and needing to lug large equipment around.

 

Lovely comfortable place to be. I could have got 50mpg in a mirca. But would have had the bonus of severe backache.

 

I will say the fly in the ointment was finding lpg stations although the app filllpg on android was really good. Used location etc.

 

Oh and the lpg fuel gauges are just crap. Always have to gauge from the mileage yourself.

[Bradders59]

Point me to the PROFESSIONALS then. 

 

Ask questions on OOF and you will get plenty of answers. Plenty of experience of LPG fitting and use on there. Particularly, The Boy, Kevin Wood and Lazydocker,

V6 Omega engines are very well suited to LPG, and don't need flashlube. I ran one for several years without any major issues.

[Bradders59]

What I've never understood is... Given LPG is such a cheap fuel, why isn't it more widespread? Why don't manufacturers offer it as a fuelling option as standard?

 

They did offer it as an option when it became popular in the 90,s then the govt. and environ mentalists decided diesel was  the best fuel to power vehicles, until they discovered it was worse than petrol. They then decided that all fossil fuels were evil and to be strongly discouraged at all costs. What we needed was lots of windmills and solar panels.

Emissions from LPG cars are miniscule in comparison with petrol or diesel, so they grudgingly give a £10 pa discount on ved.

Don't believe the stories though about LPG running costs being half what they would be on petrol.

In my experience 30% saving would be a more realistic figure.

[Bfg]

^

My own experience with the Essex Scimitar would similarly suggest an overall 30 - 40% running-cost savings over petrol, but when I had that car petrol prices were higher than diesel. 

 

As I've shared before - I reckon on at least 10% drop in engine power when running on LPG ..which is not an issue when cruising along. But when it comes to overtaking, pulling up hills, carrying heavy loads, high speed driving, etc. and/or generally driving briskly, then that ten percent equates to needing more throttle for longer.  So although the cost of LPG fuels might be close to half that of petrol then my running costs were not half - because I used more throttle. 

 

And then as stated by others - LPG filling stations are around (I had an A5 sized map of GB with LPG stations in it) but they are often just a little way off your normal (shortest route). To my knowledge there were two stations in Ipswich, a Morrison's and a Shell station, and two along the A14 route I took every other week to Kettering.   The two in town were fine if you happened to be nearby ..but a costly-in-time diversion if you weren't.  In all cases I found running on LPG took a little planning because the tank was just a little too small to drive to Kettering and back, so I always had to stop for fuel ..or else switch back onto petrol.

 

So I'd suggest the amount of savings come down to driving style (prolonged cruising versus stop-start spirited driving up n' down a hill side), the diversion off your normal routes to a LPG filling station, and to the size of your LPG tank..

 

Personally I like the environmental impact and the cleanliness, the easy starting and the spark plugs always being a perfect colour, and also the slightly less engine noise and harshness of running on LPG.  So, given the choice I would drive an LPG vehicle.  But., I drive a Chrysler Grand-Voyager diesel - which is a truly superb load carrier.  Its 2.5ltr diesel is more powerful and at 40mpg is again almost twice as economical the 3.3ltr petrol model I had previously.  The other car I own is the Ami-super, and because it is a small car without a sealed boot space - it is not a practical / economic proposition to fit LPG.  Being just 1 ltr and used for only local trips - the amortisation costs of an LPG installation would mostly likely extend to something like 20 years (..about twice as long as I'll be alive).!    However, next year I plan to change both vehicles - so then we'll see whether I can get back to running on LPG.     

 

Bfg.