Petrol vs Diesel Cost Calculator
Petrol vs diesel cost calculator compares total running costs between gasoline and diesel vehicles. Find which fuel type saves more money based on your driving distance, fuel efficiency, and local prices.
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Formula
Calculates monthly fuel spend for each vehicle type, then compares the two to show which is cheaper and by how much. Diesel typically offers 15-25% better fuel economy but costs $0.10 to $0.30 more per gallon or litre.
Worked Example
Comparing Petrol and Diesel Running Costs
- Diesel engines typically deliver 15-25% better fuel economy than equivalent petrol engines
- Diesel fuel costs $0.10 to $0.30 more per litre or gallon than petrol in most markets
- At 1,500 km/month, diesel can save around $23/month or $278/year on fuel
- High-mileage drivers (20,000+ km/year) benefit most from diesel efficiency
- Diesel maintenance costs run $200 to $500 more per year for injectors and filters
Use this calculator to compare your specific driving pattern and local fuel prices. The right choice depends on your annual mileage, fuel costs in your area, and how long you plan to keep the vehicle.
You can also calculate changes using our Fuel Cost Increase Calculator or Fleet Fuel Expense Calculator.
Frequently Asked Questions
Is diesel always cheaper to run?
Not always. Diesel vehicles get 15-25% better mileage, but diesel fuel often costs $0.10 to $0.30 more per litre. At 1,500 km/month, diesel can save around $23/month, but at lower distances the savings shrink or disappear.
Does this include maintenance costs?
This calculator compares fuel costs only. Diesel vehicles typically cost $200 to $500 more per year in servicing due to injector and particulate filter maintenance, but their engines often last 50,000+ km longer.
What about hybrid or electric vehicles?
This tool compares only petrol vs diesel. Hybrid vehicles typically use 30-50% less fuel than petrol, while fully electric vehicles eliminate fuel costs entirely but have charging costs of roughly $0.03 to $0.10 per km.
At what mileage does diesel become worth it?
Most drivers see diesel savings above 15,000 to 20,000 km per year. At 20,000 km/year with typical prices, diesel can save $250 to $400 annually on fuel alone, which helps offset the higher purchase price.
How do I convert between km/L and MPG?
Multiply km/L by 2.352 to get miles per gallon (US). For example, 14 km/L equals about 33 MPG, and 18 km/L equals about 42 MPG.
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