Autogas lpg – an alternative engine for retrofitting

LPG retrofit

LPG – liquified petroleum gas is a fuel for gasoline engines. About 400.000 cars are equipped with LPG on german roads. A car that has been converted to run on autogas will run on either autogas or gasoline. It is easy to switch between the two fuels while driving. Normally the engines start with gasoline and as soon as the engine is warm enough, the system automatically switches to autogas. In germany, numerous car companies offer LPG ex works or as a direct conversion for new cars.

What is LPG made of?

LPG, liquid petroleum gas or LPG basically consists of a mixture of butane and propane. These two main components of automotive gas are used in the extraction of crude oil, but also in the refining of diesel, gasoline and other fuels.

Retrofitting with autogas and costs

As mentioned above, there are numerous car manufacturers that offer vehicles with LPG offer as fuel. In principle, the alternative fuel autogas is suitable for cars that previously ran on gasoline. Only a few petrol cars can not be converted to LPG. Since LPG burns hotter than gasoline, sometimes the exhaust valves have to be replaced with a gas resistant version. In addition, there are solutions with additives that are injected to protect the valves.

For the conversion there are professional LPG conversion companies. The costs are about. 1.500 – 3.000 €. The price depends on the type of vehicle and engine. During the conversion, the gas system with filter, gas vaporizer, injectors and possible additive tank is installed in the engine compartment. An additional tank is also installed for the gas. Mostly wheel well tanks are used for this purpose, which find their place at the location of the spare wheel. The connection for the tank nozzle is either placed next to the usual tank nozzle behind the fuel filler flap or is installed in the rear apron of the vehicle.

Since the conversion involves modifications to the engine, the manufacturer’s warranty on the unit is voided. But reputable retrofitters take care of this 100%. Therefore, when refitting should be carefully considered.

Below is a summary of the conversion costs for specific cars: PDF

Range through LPG

The range of a car converted to LPG, as with any other fuel, depends on the size of the tank installed, which can vary from vehicle to vehicle. It should also be noted that for safety reasons, an LPG tank can only be filled to 80%. The dispenser then switches off automatically. The remaining 20 percent serves as a buffer in case of strong expansion of the gas. A 60-liter tank can therefore effectively hold 48 liters of autogas. With autogas, the vehicle consumes about 10 percent more than with gasoline. If a car consumes about 10 liters of gasoline per 100 kilometers, a vehicle that runs on autogas consumes 11 liters of LPG. With our example tank of 48 liters capacity, the range with LPG is about 430 kilometers. Since the normal gasoline tank also remains in the car, the range with gasoline is added once again. If our example vehicle fills up with 60 liters of gasoline, a total of over 1000 kilometers is possible.

How to refuel with autogas?

LPG can already be filled at many gas stations. Depending on how the vehicle has been retrofitted, an appropriate adapter must be screwed on. The nozzle can then be connected to the adapter or directly to the vehicle. Afterwards, a so-called "dead man’s switch" must be activated at the gas pump for refueling. This must be kept pressed throughout. As soon as you let go, the refueling process is finished. When the tank is 80 percent full, the system stops automatically. When the nozzle is removed, a small amount of autogas still present in the hose escapes. This is completely normal and absolutely harmless.

Maintenance costs after conversion to LPG

After the vehicle has been converted, additional maintenance costs are incurred. This includes, among other things, changing the filter, checking the connections, fastenings and hoses, and checking for leaks. This is usually done as part of the regular inspection. After accidents or fires, a gas system check is also on the program. Every two years, the LPG system is also checked during the main inspection (HU).

LPG prices and subsidies

The price per liter of LPG varies from 45 to 90 cents depending on the region. Prices are generally subject to slower and smaller fluctuations than gasoline. The tax on LPG is currently favorable. This benefit decreases every year and it is planned that from 2023 there will no longer be a tax benefit. Then the liter of autogas costs just under 15 cents more and is still well below the cost of gasoline and diesel.

LPG and the environment

In the context of the discussions about the pollutant emissions of passenger cars LPG an interesting alternative. Comparisons have already shown in 2017 that LPG vehicles emit significantly less nitrogen oxides and fine dust has also been reduced by up to 99 percent compared to gasoline operation. In addition, the CO2 values of LPG vehicles are impressive, being 15 percent lower than those of comparable gasoline-powered vehicles.

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