Few if any manufacturers offer LPG as factory option for cars (as opposed to commecials) in UK so conversion is a big cost. Tank takes up space. LPG is banned in some places including the Channel Tunnel.

Biggest users are probably urban and that's market where electric or hybrid scores best.

We've had 3 cars converted so far, the last one literally a month ago.

If anything its got more niche, as due to falling demand for conversions many fitting centres have closed down, in many ways that suits us because with such small sales the govt isn't losing much tax so hopefully they'll leave it alone, very nice filling up at Morrisons Wisbech Monday evening on the way back from the beach @ 57.9 ppl...we won't ever be filling up at BP near the Black Cat roundabout who laughingly want 72.9 ppl, cheaper at the BP Toddington MSA.

The reasons as i see it for the less conversions are...

So many cars now on long term rent via various payment schemes and the renter not allowed to do anything like this even if they wanted. More cars getting direct injection which is a real headache for converters, most of whom wont go near them. Lack of suitable spare wheel wells to site the gas tank. Getting a conversion means you intend to keep the car for a long time, keeping it well maintained for a long life, that alone seems beyond many. Having to plan where to buy fuel. Kissing goodbye to between £1500 and £2000 for the conversion where many would see that as a large portion of cost to change funds for their next new car.

The maker's supposed conversions weren't, they were done by sub contractors and invariably didn't have flashlube valve saver systems fitted, so tended to suffer valve seat recession, and in The Mitsi's case the converter went bust and used some system no one else could program or get parts for, i'd much rather a good quality conversion by an installer of my own choice.

The most recent conversion is SWMBO Subaru Forester 2.5 XT, when i filled up at Wisbech a quick mileage check showed 20mpg on gas, that was a fastish run both ways (making use of the rapid yet safe overtaking the car allows) with us two plus the usual stuff you take and three dogs, fortunately no longer wet after sploshing around in the sea at Brancaster Beach.

Oh and Saga were quite happy about the latest (registered) conversion, and no charge levied.

Edited by gordonbennet on 13/06/2018 at 19:28

My car cost £1800 to convert and in 2 years saved over £3000 . well worth it.

Must be doing a huge mileage to save this much. As an exercise, I assume LPG costs just over half petrol/diesel price, and apparently does approx 25% fewer mpg. So, with LPG costing £2-70 per gallon and p/d £5-20 per gallon, returning 30mpg and 40mpg respectively, you need 400 gallons of LPG and 300 gallons of p/d to do 12,000 miles, a saving of around £500, give or take 10%.

Clearly LPG aficionados will massage the figures to favour their choice, but I have no preference and have tried to be as objective as possible.

Garage near us sells LPG at about £0.69 a litre.

Tesco sells petrol at £1.179 a litre.

Assuming 20% less mpg if we converted both cars and used only gas on local trips our annual saving would be about £400 a year.

How many years would the conversion cost for 2 cars take to recover I wonder.

And whilst the Superb has a huge boot fitting a gas tank to the Fabia would probably mean loosing the spare wheel well so where would we carry the essential (IMHO) spare tyre and tools?

Its a total non starter which is why its never become popular.

When I said they make sense, I meant they made environmental and technical sense.

The economics are whatever the government say they are, since they are detemined by fiscal policy.

So the economics probably don't make sense.

Tits-on-a-bull-technology a la dieselle moderne, OTOH....

With demonisation of diesel occurring faster than availability of affordable electric vehicles it may make sense for manufacturers to go back to it as an option on petrol vehicles.

And/or on diesel vehicles. There are reportedly (and intuitively) significant advantages in running LPG/CNG in combination with diesel.

With a bit of tweeking it seems likely this could be a big help with the TOAB DPF systems too.

I've run three vehicles with LPG. Theoretically there are four or five Garages selling Lpg on my usual route to work. However it always seemed a lot of them had issues all the time. The pumps broke, we've run out etc. That was one reason I gave it up. Seconds I was unlucky enough to get Valve seat recession on two of the vehicles. Necessitating some head work. Great in theory but a bit of a pain in general day to day. I guess if I'd had a bigger tank in the boot rather than a toroidal and a better flash lube system maybe I'd still be using it. I agree it's a damn shame it's not much more popular . Good way to run a big engine cheaply. Sadly you still get caned by HMRC for vehicle tax despite being greener. That and dont forget you also have to have the system annually serviced. Replace the tank every something years though I didn't. Oh and I seem to recall it's a good idea to fit iridium plugs Not Platinum as lpg eats it...Hope that helps.

If it were not niche it would likely be taxed at levels similar to petrol and diesel - manufacturers know this and I assume do not generally want the hassle of engineering an emissions compliant reliable solution for no real benefit.

Assuming the above is the case, most people would not contemplate an LPG conversion to a vehicle that was still in the warranty period as it would probably be invalidated.

Therefore most conversions will happen on cars 3+ years old. Typical conversion costs of around £2k would be a significant add-on cost of vehicle acquisition.

It may make sense for a large uneconomical vehicle if you plan to keep it for 3-5+ years and do a higher mileage - otherwise:

• servicing could be a hassle
• lingering doubt over impact on engine reliability
• may not be able to integrate with existing vehicle electronic systems
• may lower resale value as perceived as unquantifiable risk
• fewer refuelling points

A contractor friend of mine bought a new Transit from a Ford dealer converted to run on LPG thus I can only suggest it was either factory fitted of a factory approved dealer fit system.

Over the 3 years he ran it he became convinced diesel was still a better option for him despite the cheaper fuel, in fact every Transit he has bought since has been a diesel.

But the main problem was the air filter box. At regular intervals the lid simply blew off despite being securely fixed and it was after all the standard Ford airbox. The dealers solution was simple, to prevent it blowing off they put a number of tie wraps (zip ties) round the air box and it never happened again. Not very reassuring when they never cured it other than with a bodge.