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PHEV petrol and electricity cost requires two energy records. A very low weighted fuel-consumption rating is not the entire running cost and is not a promise of petrol-only economy when the car is rarely charged. This article builds a simple monthly scenario, then explains why actual blended operation should be measured. It complements the EV-versus-petrol tool rather than claiming that tool simulates every PHEV mode.
Record the inputs before calculating
Gather total distance, wall electricity used for charging, fuel consumed, charging prices and petrol prices for the same period. Where measured totals are available, calculate each cost directly. For a forecast, use vehicle-specific electric and charge-sustaining consumption and an explicit charging pattern. Do not add charging losses again if the electricity consumption is already measured at the wall.
Worked example and formula
Illustrative numbers only. Replace every assumed measurement, price, rate and performance factor with evidence for your situation. A 2026 review date does not turn an example into a current market quotation.
600 km × 20 kWh/100 km / 100 = 120 kWh
400 km × 6 L/100 km / 100 = 24 L
120 × 50 PKR/kWh + 24 × 300 PKR/L = PKR 13,200
1,000 km × 6 L/100 km / 100 × 300 PKR/L = PKR 18,000
The fictional 1,000 km month assigns 600 km exclusively to electric driving at 20 wall kWh/100 km and 400 km exclusively to petrol operation at 6 L/100 km. At PKR 50/kWh and PKR 300/L, it costs PKR 13,200. The simplified petrol-only comparison at 6 L/100 km costs PKR 18,000. These mode assumptions and prices do not describe any named PHEV or current tariff.
Interpret the result correctly
Real PHEVs can burn fuel during nominally electric trips, depending on vehicle and conditions. In that case record both energies for the same distance rather than force all kilometres into exclusive modes. Keep public charging fees, parking, maintenance and purchase-price differences separate. A change in charging frequency does not guarantee the same petrol consumption assumed in the illustration.
Keep the original measurements, source date, units and assumptions beside the result. Change one assumption at a time to see its effect. A comparison is meaningful only when both options use the same scope. Do not silently combine different test procedures, products, dates or fee bases. Round a purchasing quantity upward only after completing the calculation; retain enough precision for intermediate steps.
Frequently asked questions
Which measurements should I use?
Use electricity and petrol measurements covering the same period and distance, including blended operation.
Is the example a guaranteed result?
No. Both prices and mode-specific consumption are illustrative; your charging access and route can change the total.
What should I check before acting?
Check wall-versus-battery energy, charging frequency, engine operation and the tariff actually paid.
Use the result and related tools
Use the EV-versus-petrol tool to explore separate scenarios and its assumptions. For a PHEV, maintain a combined worksheet and add both measured energy costs; do not present one tool output as a full PHEV simulation.
Sources and review scope
Reviewed 22 October 2026. The examples and arithmetic are original editorial illustrations, not field tests, certified designs, current price surveys or promised savings. Sources support the stated concepts; they do not certify these example inputs. The linked calculators have their own assumptions. These articles address specific decisions and complement the existing calculator guides. No Google search-volume or ranking claim is made.