Any - LPG or Diesel - chanlfc

I am looking to get a used car for upto 10K, I do around 20K miles a year and looking for a family exec car.

Thinking of 08/09 plates in:

Honda Accord / Mazda 6 / Maybe a BMW 3 / Audi A4

Obvious choice is Diesel, but after reading about numerous problems with DPF's and the costs associated in fixing I am put off with it all.

Which made me think of a buying a petrol car (in theory) being approx 1K cheaper than the equivalent diesel, and get it converted to LPG.

So my question is are those cars I mentioned actually suitable for LPG systems, as I heard not all makes and models are. Is anyone aware of LPG issues like the DPF's in diesels? and finally is it not just worth the risk on either Diesel or LPG and stick to petrol and take the hit on extra fuel costs but less garage repair bills.

Any advise appreciated, thank you

Any - LPG or Diesel - RT

DPFs are only a problem for those doing low mileages, ie short runs, the very sort of people that shouldn't be buying a diesel in the first place!

Any - LPG or Diesel - jamie745

LPG is brilliant for keeping old, thirsty cars somewhat viable. Old Jaguars, Jeeps, LandRovers etc which were originally bought when petrol was 50p a litre. If you're spending serious money and doing a big mileage then you shouldn't have any problem with a modern diesel.

Any - LPG or Diesel - TR7
The problem is buying a second hand diesel 2-3 years old you don't really know how it's been driven. I do up to 40k a year and bought a facelift 2008 focus 1.6tdci with 50k on the clock at 64k the dpf packed up.

Edited by pkqpr on 29/01/2013 at 19:12

Any - LPG or Diesel - chanlfc

Its my point exactly, it depends how people have been driving it before I buy it. With petrol it wont make a difference in that respect.

LPG is still more economical than diesel as its only 63p litre near me and diesel @£1.40.

LPG does do about 10 to 15% less mpg to petrol but still is cheaper according to those fuel calculators online.

This is my reason behind my thinking of a LPG system. But not sure if suitable for Honda's /Audis.

Anyone with LPG knowledge hopefully can help.


Any - LPG or Diesel - unthrottled

Prins have a list of engines that they deem unsuitable for LPG conversion-and it is fairly extensive. Most of the problems were down to valve seat recession. It seems that manufacturers realised that their valves were overengineered for running on petrol. With 4 valves/cylinder a useful cost saving could be realised by substituting cheaper ones.

I'd expect a bit more than 10-15% loss in economy on LPG. More like 20%, Still a cost saving in running costs, but payback is a little longer.

Any - LPG or Diesel - gordonbennet

My only problem with LPG is wondering why i didn't make the change years ago, previously have had at least one Diesel since the early 80's.

We have bought a second LPG car now an 04 plate Outlander LPG'd by the maker/importer when new, it was bought because we decided that we don't wish to buy into the modern Diesel and its problems any more, and with a petrol engine you get a better choice of real autos.

My MB which is an older W124 coupe runs as smoothly on LPG as it does petrol and the performance whilst losing its sparkle is still more than adequate for all my needs and will still surprise the owners of modern rapid cars...its a 3.2 24v that i use to commute to work and the odd trip it gets driven quite briskly, just filled up today 55 litres cost me around £42 and the trip meter read 260 mile, its had quite a bit of hard and snow driving so slightly heavier on the juice than usual.

Remember whilst VED is CO2 based the equivalent petrol is higher rated, though i expect that to change following recent revelations from the climate warming lobby that Diesels cause all sorts of nasties.

LPG could be frustrating if you bought a car only just powerful enough.

You need somewhere to put the tank which for most users means a toroidal tank in the spare wheel well (so make sure its got a decent wheelspace, BMW?) and that may be a relatively small tank, i don't need the whole of the huge MB's boot so have an 80 litre cylinder tank bolted across the rear bulkhead.

Don't go too far from your home looking for a converter, you'll want it servicing and it might need adjustments for fine tuning at first, recommendation is everything here, cheapest may not be best.

You may need a flashlube system to help prevent valve burn, Japanese cars not as forgiving as my bombproof old MB though i have one anyway belt and braces, your converter will know.

He did say that generally German cars take to the conversion well, little in the way of valve seat probs, though he was referring to MB at the time, i couldn't say what other makes but he did say when i enquired that Lexus' he has converted have been no trouble whatsoever.

Direct injection engines are not suitable due to the petrol injectors getting cooked.

Until dick turpin decides to raise the taxes on LPG substantialy, probably when the country goes broke with ensuing anarchy in the next few years, i shall continue with LPG, its not for everyone but suits us fine.

Edited by gordonbennet on 29/01/2013 at 20:12

Any - LPG or Diesel - skidpan

There are diesel cars available that are early 60 plate that have no DPF or DMF fitted. You have to choose carefully.

LPG is fine if there is a station handy that sells the stuff but if you are doing 20,000 miles a year I guess that includes long trips thus you may discover finding it is a chore.

It robs boot space thus you need an even bigger car than normal.

We have had a diesel in the house for 5 years with a DPF and no issues with it whatsoever. Does about 7000 miles a year and does a regen when it needs to. Calculate I have saved about £2300 on fuel and tax in that mileage. Car only cost £300 more new than equivalent petrol and is worth more than the equivalent petrol now.

Personally I like the way a turbo diesel drives, I find modern petrols rather gutless unless you get a big gas guzzling engine. Stick LPG on one and you do loose a little power, that can only make the drive worse.

Each to their own but there are a lot of people on this site who dislike diesels for no genuine reason.

Any - LPG or Diesel - glowplug

So long as you way up the drawbacks of LPG it could be the way to go.

Don't forget that adding a LPG system to a modern fuel injected car adds another layer of complexity to it. After owning a 'certified' LPG car I would say that you need to pick the car, the installer and LPG system very carefully. Yes you need it servicing but a poor local installer is a far worse option than a quality service miles away. Genuine references are everything with LPG installs. If the car develops a fault with it's native petrol system then expect the fault to be magnified with LPG. As well as losing power you'll also lose MPG with a LPG system.As noted by others you'll lose space somewhere and filling up can be a slow process depending on the tank type.

Alternatively go for a diesel and have the EGR/DPF bypassed and mapped out.



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