This is a conversation we have at the shop all the time: "It is burning too much gas." I ask how much. They say 12 liters. What car? Golf 5, 1.6 petrol. That is perfectly normal. LPG always uses 15 to 20 percent more per liter than gasoline because it has a lower energy density. But when consumption climbs to 15, 16, 17 liters, then something is not right. Let us go through what affects it.
System Calibration
This is by far the most common reason for excessive LPG consumption. The maps in the LPG controller determine how much gas goes into each cylinder and at what moment. If those maps are not set correctly, the engine either gets too much gas (rich mixture, higher consumption) or too little (lean mixture, power loss, so you press the throttle harder).
Calibration drifts over time. Injectors wear out, the reducer changes its characteristics slightly, and the maps that were perfect a year ago are no longer optimal. That is why recalibration is part of every routine LPG service.
Filter Condition
The LPG system usually has two filters, one in the liquid phase (before the reducer) and one in the gas phase (after the reducer). When a filter gets dirty, gas flow decreases. The controller compensates by keeping the injectors open longer, but that throws off dosing precision. The result is higher consumption and rougher engine performance.
Filters should be replaced every 10,000 to 15,000 km. They cost 15 to 20 KM, and the difference in consumption can be as much as a liter per 100 km.
Injector Wear
LPG injectors have moving parts that wear over time. When an injector loses precision, it does not close fully or does not open fast enough. That means one or more cylinders get the wrong amount of gas. The engine compensates, but at the cost of higher consumption.
Ultrasonic cleaning of the injectors brings them back into tolerance for a while. Full replacement is usually needed around 80,000 to 100,000 km, depending on the quality of gas you use.
Driving Style
This applies to gasoline too, but on LPG the effect is more pronounced. Aggressive acceleration and high revs use significantly more fuel. LPG burns most efficiently between 2,000 and 3,500 RPM. A driver who keeps calm and reads traffic ahead can save 2 to 3 liters per 100 km in the city.
City vs. Open Road
City driving always means higher LPG consumption. Constant stopping and starting, a cold engine running on gasoline until it warms up, short trips. On the open road at a steady 90 to 110 km/h, you get the best consumption numbers. That is where the real savings from LPG show up.
Winter
Consumption goes up in winter for several reasons. The engine takes longer to warm up, so it runs on gasoline longer. The LPG reducer needs more time to reach operating temperature. Denser air and winter tires with higher rolling resistance push consumption up further. The difference between summer and winter can be a liter or two per 100 km.
Tire Pressure
Sounds like a small thing, but tires inflated 0.3 to 0.5 bar below the recommended level can increase consumption by 5 to 8 percent. On LPG, that is noticeable. Check your pressure at least once a month, especially when temperatures change.
Engine Air Filter
A dirty engine air filter directly affects LPG consumption as well. The engine does not get enough air, the mixture runs rich, and the controller tries to compensate. The air filter gets replaced at every basic service. Do not skip it.
How to Lower Consumption
The fastest way to bring consumption down: bring the car in so we can check the calibration and swap the filters. That alone usually drops consumption by a liter or two. The rest is up to you. Smooth driving, regular maintenance, and proper tire pressure.
If you think the car is using more than it should, get in touch and we will measure it and compare against normal values for your model.