I’m thinking of getting an impreza sportwagon with a brand new Prins LPG conversion. However, i have not had LPG before and am after some feedback from those that have. It seems a good way of getting a decent performance petrol car but with lower costs.

Is it worth it?

cheers

Rich

My Lexus 430 is LPG converted. No impact on performance (despite a 4.3 litre engine), fuel consumption is slightly worse, but more than offset by the lower cost.

Cons – only have a 60 litre tank, and do 500 miles a week, so have to fill it up regularly. filling is a bit smelly, and there is a knack to the various different nozzles at filling stations. I have run out of petrol twice, as you use so little of it (just to warm up the engine)and forgot…nothing negative really – go for it!

In short / reality:

You’ll get about 80 to 85% performance from it compared to petrol … that includes mpg aswell.

An LPG tank is often smaller in capacity than the normal petrol tank fitted to the vehicle, so factoring that plus reduced mpg can equal shorter range between fill ups. Do the maths in that respect to give you a good idea of how often you’ll fill up.

Also do some looking into where the local LPG stations are and what times they open. If you have to go out you normal way to fill up, then factor that in too … it can be a PITA if you have to do that and even more so when they only open during normal hours.

I don’t know about impreza’s but some engines ( parts like the valve seats ) don’t like the higher temperatures that LPG can burn at, and to counter it they install flash-lube systems … so that’s another possible expense and something to look at / check out for running cost.

On the plus side: It is defo a cheaper way of running a car, and if fitted properly, its unnoticeable when it changes over between fuels.

I liked having LPG fitted, but for me, there was no local stations, and the shorter range made it too much hassle in the end. So I went down a diesel route this time.

Lastly … is the a premium being added to the car for the LPG kit? If so, consider how much? and then consider how much petrol that would buy you in terms of running a non-LPG version … if might not be worth it?

Why has the owner gone to the expense of fitting a brand new kit just to sell up would be my worry.

They can be problematic to set up.

I have a basic single point set up on my v8 landy but dont like using it for the higher temp as fisha mentions just havnt got round to tearing it out.

On the plus side: It is defo a cheaper way of running a car

its only a cheaper way of running a petrol car. If theres a diesel alternative of the car you want the the savings are likely somewhere in the range of negligible, nil or negative.

I did about 80,000 miles in a single point injection system in a V8 range rover with no problems, but badly fitted ones can be a nightmare, if gas builds up in the manifold it can detonate back up the inlet tract causing varying amounts of destruction. Shouldn’t be a problem with multi point systems.

Like the others have said power will be a bit down and mpg slightly higher but its a lot cheaper. Engine runs cleaner, but not much reduction in CO2 output.

Range can be a problem, depending on the tank arrangement. Advantage of the RR was that it was big enough to keep the petrol tank plus two torpedo gas tanks on the chassis rails and a big one in part of the boot, but if you are short of space it might mean losing petrol capacity or the ability to carry a full size spare wheel. You get to know where LPG places are, there used to be a an online list of them, probably still there somewhere. It might not be much benefit if you don’t have much capacity and LPG stations are thin on the ground near you.

Trail rat – the car has just been professionally converted by an LPG specialist so i have no worries regarding the conversion itself.

I have a diesel at the moment, the problematic DV6 one, and am getting frustrated by the complexities of the modern diesels. DPF’s and increasingly smaller engines and larger turbos to get the higher mpg and meet emissions mean that, IMHO, potential repairs can be huge. I dont mind sacrificing some economy for reliability, which i feel i would be getting from an older japanese petrol- but would LPG be potentially unreliable!?

The points made are really useful and it seems its down to the sums as to the viability!

We run several LPG converted Mitsubishi shoguns and others as farm vet cars. As such they do a decent mileage and get a bit of abuse. If the conversion is done well they do last well. Somebody currently tootling around in a Y reg one and a 03 and 04 plate still in use too.

Buy the petrol ones very cheap secondhand then get them done, buy the LPG in bulk into a central tank too.

I have a diesel at the moment, the problematic DV6 one, and am getting frustrated by the complexities of the modern diesels. DPF’s and increasingly smaller engines and larger turbos to get the higher mpg and meet emissions mean that, IMHO, potential repairs can be huge. I dont mind sacrificing some economy for reliability, which i feel i would be getting from an older japanese petrol- but would LPG be potentially unreliable!?

Then either buy a more efficient petrol engined car (Scooby’s are not very). A newish 2.0i rep-can should hit 40mpg.

Or go cheaper, decent 2.5-3.5 petrol cars can be had cheap, as in under £2k for low-mileage good condition.

I dont mind sacrificing some economy for reliability, which i feel i would be getting from an older japanese petrol- but would LPG be potentially unreliable!?

If it’s installed professionally by a reliable fitter then it shouldn’t be unreliable.

I would say that the only thing you need to be careful of is LPG drying the engine out – regular oil changes are a good idea (like every 5 – 6000 miles) and run it solely on good quality unleaded every now and again – something like Optimax or V-Power.

Bear in mind that unless you are doing regular long trips you probably won’t see any economic benefits at all – LPG systems start up on petrol and take a couple of miles to switch over fully onto gas once they are warmed up.

I ran a Volvo S70 on a single-point ssytem for about 3 years with no problems. I don’t subscribe to the reduced performance argument, it felt no different in response/torque over running it on neat petrol. I do agree that consumption figures will be down over petrol by about 10 – 15%.

Tank-wise, a donut tank in the spare wheel well will allow you to keep full load space at the expense of being able to carry a spare wheel, so you may need to budget in for run-flat tyres too unless you want to carry a can of tyre-jizz and a compressor, or rely on the breakdown services.

45000 miles so far with no issues.

The filters and system should be serviced yearly which adds some costs. Can be upto £80
Be sceptical of some dealer figures. You will not get double the mileage compared to petrol

With our unleaded start up use (some people recommend to always keep quarter of a tank of unleaded to stop the fuel pump running dry) and the slight loss of economy by using LPG we have ended up with around 45-50 mpg comparatively (real world comparison using top ups and mileage not car computers. The cars book figures are 30mpg)
Lot’s of short and long trips but the economy has remained fairly consistent.

This is better economy than we got from a diesel version of the same car so pretty happy with that side of things.

Small doughnut tank in spare wheel which gives around 250 miles until refill

Engine servicing has been required less due to the engine running cleaner.
I have noticed no difference in power though it could be true that there is a small loss.

Bit of a faff with some nozzles and filling does seem to take that little bit longer. I live in the countryside and there are loads of LPG stations all around me but on some trips you will need to have a quick look at an online map to get a rough idea of fuel stops.
The digital fuel gauge we have is pretty poor so we use the mileage counter to plan our refills

Shop around you should be able to get a car with an LPG system and pay a very minimal premium.

I now cry when I have to put unleaded in!

I don’t agree with the 80-85% performance figure quoted above at all – the one I’ve seen elsewhere, and seemed right when I ran an LPG vehicle was 2% drop on performance. Ask yourself whether you’d really notice / be bothered by a 2% loss in power? 80% fuel consumption sounds about right though.

That issue of range is, or can be, the biggie. Gas tanks don’t “fill to the brim” like a liquid fuel tank, so if you’ve been told it’s got a 50 litre tank, assume you can get 40 litres of fuel into it.

You will need to know where your local LPG supplying garages are, and a bit more planning is required for out-of-area journeys as you’ll want to know where you can fill up. You can buy a little road atlas that tells you where all the LPG stations are, and they send online updates through the year of changes. I only ever nearly got caught short on fuel once, but once was still worrying and if the effect is that you have to travel out of your way to get fuel, that can be PITA itself.

This is likely to be more of an issue on a smaller car where the tank mounting options are more limited, not so bad for big 4x4s where you can have big tanks. Also, assume that you will no longer have a spare wheel, which might be a nuisance if you need it.

I had LPG on a 4 litre Jeep, I was happy with it, apart from having to stop for fuel far too often, but I haven’t missed the faff of finding stations since I switched to a Diesel car.

You shouldn’t have any technical worries about a professionally fitted Prins multi-point, they’re good (that’s what I had!). The filling procedure is a bit more faff than petrol / diesel and there’s a couple of different pump types out there but, to be honest, once you’ve done it a couple of times you’ll be fine, it’s not THAT hard…

You can buy a little road atlas that tells you where all the LPG stations are, and they send online updates through the year of changes

You can download a guide from the LPG Installers Association website.

You can also buy LPG at gas suppliers as well as filling stations. Many caravan dealers sell LPG, as well as people who supply bottled gas for heating/cooking/camping etc. I used to get mine from FlowGas in Burnley, it was about 2p per litre cheaper than buying it off a forecourt.

theocb – Member
45000 miles so far with no issues.

Sister in laws car has it. 4 litre Ford Fairlady or Fairline something like that. LPG costs 70c here in Oz. The car’s done 260k km. Fires up on petrol, drive for a few mins then switches over to LPG.

Range Rover Classic 3.9l V8 with multipoint system and 2 belly tanks.
Minimal performance difference and actually a bit smoother on gas.
Biggest problem for me ws availability locally. Only a couple of places selling gas and both were a 10 or so mile drive away.

Not directly but avoid this….
Hose fun…