LPG, petrol or diesel: the comparison
If you are thinking about LPG, you mainly want to know: what do I save, and what do I have to accept in return? This comparison shows the key differences from petrol and diesel.
Consumption
LPG contains less energy per litre than petrol. A vehicle running on gas therefore uses roughly 15 to 25 percent more, measured in litres, than on petrol. The exact figure depends on the engine, the system and how you drive. The lower price per litre normally more than makes up for the higher consumption.
Cost per 100 kilometres: a worked example
The figures below are example values, not current prices. Put in the prices from your own filling station and the calculation will fit your case.
| Fuel | Consumption / 100 km | Price per litre (example) | Cost / 100 km |
|---|---|---|---|
| Petrol | 7.0 l | €1.80 | €12.60 |
| LPG (+20 %) | 8.4 l | €0.95 | €7.98 |
| Diesel (different car) | 5.5 l | €1.70 | €9.35 |
In this example LPG saves about €4.60 per 100 kilometres compared with petrol. Over 15,000 kilometres a year that would be around €690. To see how quickly a conversion pays for itself, use the payback calculator (in German).
Range
With an LPG system the ranges of the petrol and gas tanks add up. Depending on the design, a gas tank usually holds between 40 and 80 litres of usable volume, since only about 80 percent of the tank volume is filled. A diesel car often goes further on one tank than a car on gas alone, but has no second fuel as a reserve.
Power and driving
On gas the engine usually produces slightly less power than on petrol; depending on the system the difference is a few percent and hardly noticeable in everyday driving. LPG has a high octane rating, which suits the engine.
Other differences
- Purchase: diesel cars are often more expensive to buy than comparable petrol cars; with LPG the conversion cost comes on top.
- Taxes: in Germany the tax reduction for LPG ended at the end of 2022. Check the current rules before you calculate.
- Station network: LPG is less widely available than petrol and diesel. Plan long trips, see travelling with LPG.
- Boot space: a cylindrical tank takes up luggage space; a toroidal tank in the spare-wheel well does not.
- Environment: details in LPG and the environment.
Conclusion
LPG is worthwhile mainly for high-mileage drivers with a petrol car, where the price gap to petrol is large enough. If you drive little or have hardly any stations nearby, you will barely recover the conversion cost.