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Diesel vs Petrol Car & Ute Breakeven Payback Calculator

Compare fuel efficiency, fuel prices, and purchase price premiums to find your exact breakeven point.

Input Parameters

km
$/L
$/L
L/100km
L/100km
$

Extra price difference paid for the diesel engine option

Calculation Results

Annual Fuel Cost (Diesel)
$2,995 / yr (1440 L)
Annual Fuel Cost (Petrol)
$3,762 / yr (1900 L)
Net Annual Fuel Savings (Diesel)
$767 / yr saved
Breakeven Payback Period
4.6 years (~55 months)
Fuel Cost per 100 km
Diesel: $14.98 | Petrol: $18.81
5-Year Total Spend (Incl. Vehicle Price Premium)
Diesel: $18,476 | Petrol: $18,810 (Net: +$334 saved)
Summary: Driving 20,000 km/year, diesel saves $767 in fuel each year. Offsetting the $3,500 diesel purchase price premium takes 4.6 years (~55 months). Over 5 years, the total cost difference is a net saving of $334.

Visual Growth Breakdown

Step-by-Step Calculation Solution
1.Annual Petrol Spend = (20000 km / 100) × 9.5 L/100km × $1.98/L = $3762
2.Annual Diesel Spend = (20000 km / 100) × 7.2 L/100km × $2.08/L = $2995.2
3.Annual Fuel Difference = $3762 - $2995.2 = $766.8/year
4.Breakeven Years = Vehicle Price Premium ($3500) / Annual Fuel Savings ($766.8) = 4.56 years

Formula & How Diesel vs Petrol Car & Ute Breakeven Payback Calculator Works

Mathematical Formula
Annual Savings = (km/100) × [Petrol_L × $/L_petrol - Diesel_L × $/L_diesel] | Payback Years = Diesel_Premium / Annual_Savings

Diesel engines are typically 20% to 35% more fuel efficient than equivalent petrol engines due to higher compression ratios and greater energy density per litre of diesel fuel. However, diesel fuel prices and initial vehicle purchase premiums must be offset by high annual mileage to achieve net financial savings.

How to Calculate Diesel vs Petrol Car & Ute Breakeven Payback Calculator (Step-by-Step)
  1. Enter Annual Driving Distance (km/year) (km): Input your target parameter value.
  2. Enter Petrol Price ($/Litre) ($/L): Input your target parameter value.
  3. Enter Diesel Price ($/Litre) ($/L): Input your target parameter value.
  4. Enter Petrol Vehicle Fuel Consumption (L/100km) (L/100km): Input your target parameter value.
  5. Enter Diesel Vehicle Fuel Consumption (L/100km) (L/100km): Input your target parameter value.
  6. Enter Diesel Vehicle Purchase Surcharge ($) ($): Input your target parameter value.
  7. Apply Formula: Calculate using Annual Savings = (km/100) × [Petrol_L × $/L_petrol - Diesel_L × $/L_diesel] | Payback Years = Diesel_Premium / Annual_Savings.
  8. Review Results: View exact computed answers, metrics, and worked mathematical proofs.
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Frequently Asked Questions (FAQs)

How much more fuel efficient is diesel compared to petrol?

Modern turbo-diesel engines consume roughly 20% to 30% less fuel (in L/100km) than comparable petrol engines, particularly under highway cruising and heavy towing conditions.

How many kilometers per year make diesel worth it?

In Australia, driving over 15,000 to 20,000 km per year typically achieves a payback on a $3,000–$5,000 diesel purchase premium within 3 to 5 years.

Official Regulatory & Government Data Sources

Authoritative Standards & Verified Reference Citations

Independent & Verified

Calculations and mathematical logic on this page are grounded in published statutory rules, regulatory standards, and official government data published by the following bodies:

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