Beginner’s Guide to LPG Conversions

The idea of converting petrol powered cars to run on LPG isn’t new but it has never caught on in a particularly big way, either. A minority of UK filling stations offer LPG – usually at about 50%-60% of the price of unleaded petrol.

You may be wondering whether an LPG conversion would be worthwhile for your car. My answer is “maybe” – but let me explain a little more before you make your decision.


LPG Conversion

Using LPG requires a new fuel tank to be fitted to your car. This is often placed in the boot or in the spare wheel location. The result is that you will lose luggage space or will have to find a new home for your spare wheel.

The conversion also requires some modifications to the engine. The end result is that your car will run on petrol or LPG – you can usually operate a switch to change between fuels.

A typical LPG conversion costs between £1,500 and £2,500.

Your LPG conversion will need to be serviced by a qualified LPG mechanic once a year or every 12,000 miles – but most regular garages don’t do LPG work, so you may not be able to combine it with your regular car services.

Only petrol engines can be converted to LPG.


Using LPG Fuel

The best part of an LPG conversion is filling up with fuel. LPG tends to be about 55% of the cost of unleaded petrol.

LPG emissions are less polluting than petrol emissions and you will find that your engine is quiet and smooth. Performance should be roughly the same in most situations.

Increased fuel consumption: LPG does not have quite as much energy per litre as petrol, which means your fuel consumption will rise when using LPG. Estimates vary, but a good guess is 20% – so you will use 20% more fuel than when running on petrol.


Does an LPG Conversion Save Money Overall?

You can work out whether an LPG conversion will save you money by comparing the cost of the conversion with the money you will save on fuel each year. As a general rule, LPG conversions are most cost effective in cars with large engines.

For example, let’s say you have a car that does 25mpg and you drive 12,000 miles per year:

Example conversion cost: £2,000

Annual fuel cost (petrol, 128.9p/litre): £2,809

Annual fuel cost (LPG, assumed 20% increase in fuel consumption, 0.749p/litre): £2,016

Annual saving = 2809-2016 = £793

At that rate of saving, it would take nearly three years for an LPG conversion to pay for itself. Until then, your LPG car won’t have saved you a penny, although it may have helped the environment a little with its cleaner emissions.

Although this is just one example, it highlights how carefully you need to consider whether an LPG conversion is worth the cost and effort for you and how long it will take you to get your money back.

Ask yourself how long you are likely to keep your current car when considering the switch to LPG. An LPG conversion will not add to the resale value of most cars.

One thought on “Beginner’s Guide to LPG Conversions

  • May 13, 2016 at 10:16 am

    First of all the average cost of a 4 cylinder lpg conversation is around £1000 and 6 cylinder around £1300. So this figure is incorrect to start with!

    Also I have resold many lpg cars and typically it adds around £500 to the resale value and also it becomes more sellable to those people that want to purchase an lpg car.

    Based on 12000 miles, think now days most lpg conversation will return money within 12 to 14 months.


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