How to Calculate Fuel Cost
Knowing your fuel cost before a trip helps with budgeting, comparing routes, and evaluating whether driving versus other transport is financially sensible. The calculation requires three inputs: distance, your vehicle's fuel economy, and the current fuel price.
The Calculation Protocol
Metric: Fuel = (Distance (km) ÷ 100) × L/100km
Total Cost = Fuel Used × Price per Unit
Fuel Economy Benchmarks
Typical Fuel Economy by Vehicle Type
Small petrol car: 35–45 MPG (6.2–6.7 L/100km). Midsize sedan: 28–35 MPG (6.7–8.4 L/100km). SUV/crossover: 22–30 MPG (7.8–10.7 L/100km). Pickup truck: 15–22 MPG (10.7–15.7 L/100km). Hybrid: 45–60 MPG (3.9–5.2 L/100km).
Factors That Reduce Fuel Economy
Highway driving is typically 20–30% more efficient than city driving due to reduced stop-start cycles. Speed matters significantly: driving at 80 mph uses approximately 25% more fuel than at 60 mph due to aerodynamic drag. Air conditioning reduces economy by 5–15% in city conditions. Each additional 100 kg of cargo reduces economy by approximately 1–2%.
Converting Between MPG and L/100km
To convert MPG to L/100km: divide 235.21 by the MPG figure. To convert L/100km to MPG: divide 235.21 by the L/100km figure. A car achieving 35 MPG = 235.21 ÷ 35 = 6.72 L/100km. Note that UK MPG uses imperial gallons (4.546 L), while US MPG uses US gallons (3.785 L) — the same physical car has different MPG figures in each system.