We hear this question almost every day. Someone is buying a car and wants to know which one pays off more. The answer is not straightforward because it depends on how you drive, how much you drive, and how much you are willing to invest in maintenance. Here is an honest breakdown from people who repair both types every single day.
Advantages of Diesel
Fuel economy is still the biggest advantage of diesel. On the open road, a good diesel uses 4 to 5 litres per 100 km, while a comparable petrol engine uses 6 to 7. If you drive a lot, that difference adds up by the end of the month.
Torque is higher at low RPMs on a diesel. That means better flexibility while driving, easier overtaking, and fewer gear changes. For towing a trailer or frequent trips with a full car, diesel is still the winner.
Engine longevity - diesel engines are built for heavier loads and generally last longer. The engine block is more substantial, and the internal components are more robust.
Disadvantages of Diesel
More expensive repairs are a reality. The DPF filter, EGR valve, turbo, injectors, high-pressure fuel pump - these are all components that cost serious money when they need replacing. A single common rail system failure can cost as much as several services on a petrol engine.
Bad for short trips - if most of your driving is 5 to 10 km to work and back, the diesel engine never warms up properly. The DPF filter does not regenerate, the EGR clogs up, and the oil degrades faster. City driving is the worst enemy of a diesel engine.
More complex system means more things that can go wrong. Modern diesel technology is precise and does not tolerate poor maintenance.
Advantages of Petrol
Cheaper maintenance and repairs - petrol engines are simpler, parts are less expensive, and mechanics find them easier to work on. A basic petrol service costs less than a diesel one.
Better for city driving - a petrol engine warms up faster and does not have DPF or EGR problems. If you mostly drive around town, petrol is the logical choice.
LPG conversion option - a petrol engine can be converted to run on LPG, which significantly cuts fuel costs. With LPG, running costs can actually be lower than diesel.
Disadvantages of Petrol
Higher fuel consumption on longer trips. A petrol engine uses 20 to 30 percent more than a comparable diesel, especially on the motorway.
A Rule of Thumb for Your Decision
From our experience, the threshold is roughly 15,000 kilometres per year.
Under 15,000 km per year - go with petrol, or petrol with LPG. A diesel in that kind of driving pattern creates more problems than it saves on fuel. With LPG, fuel costs are minimal.
Over 20,000 km per year with plenty of open-road driving - diesel makes sense. The fuel savings are significant, and the engine runs in the conditions it was designed for.
Between 15,000 and 20,000 - it depends on the type of driving. If it is mostly city, petrol. If it is longer trips, diesel.
The Most Important Thing
Regardless of which engine you choose, maintenance is the key. A well-maintained petrol engine will cost you less than a neglected diesel, and the other way around. If you are thinking about buying a car or converting a petrol engine to LPG, get in touch for advice. We will help you make the right call for your situation.