Electric vs Petrol: Running the Total Cost of Ownership Properly

Comparing an electric car to a petrol one on sticker price answers the wrong question. Ownership cost is dominated by depreciation, then energy, then servicing, insurance and tax. Run those five lines over the period you will actually keep the car and the comparison usually resolves cleanly — but not always in the same direction, because one input dominates everything.

Depreciation: the line that decides it

For most private buyers, depreciation is the largest cost of car ownership, exceeding fuel and servicing combined. It is also where electric and petrol have diverged most unpredictably. Rapid improvement in range and charging speed makes older electric models less desirable faster, and manufacturer price cuts on new models drag used values down immediately. Petrol depreciation is slower and better understood, but faces long-term pressure from emissions rules and city access restrictions.

The practical implication is that buying used shifts the maths substantially. A three-year-old electric car has absorbed the steepest part of the curve, and if the battery health is verified, the remaining ownership cost can be very low. A new electric car held for three years is the most expensive way to own one, and that is the comparison most reviews implicitly make.

Energy: entirely dependent on where you charge

This is the fork in the road. Charging at home on an off-peak tariff is dramatically cheaper per mile than petrol — commonly a small fraction of it. Charging predominantly at public rapid chargers costs several times the home rate, and at the top end approaches or matches the per-mile cost of an efficient petrol car once you account for the price premium on rapid charging.

So the honest first question is not which car, but whether you can install a home charger. If you have off-street parking, the electric case is strong. If you park on-street with no reliable charging, the running-cost advantage largely evaporates and the convenience cost is real. Workplace charging sits in between and is often the deciding factor for people without driveways.

Efficiency also varies more than people expect. Cold weather reduces electric range materially, particularly on short trips where cabin heating dominates. Motorway speeds hurt electric efficiency more than petrol, because aerodynamic losses are not offset by regeneration. A car that is efficient in town may be mediocre on a long commute.

Servicing and consumables

Electric drivetrains have far fewer wearing parts: no oil changes, no cambelts, no exhaust or emissions systems, no clutch. Brake pads last longer because regenerative braking does most of the deceleration. Scheduled servicing is genuinely cheaper, typically by a wide margin over several years.

Two offsets. Tyres wear faster on heavier cars with instant torque, and electric cars are heavier — this is a real recurring cost, not a rounding error. And out-of-warranty repairs to high-voltage components are expensive and concentrated in fewer specialist workshops, which matters most for older cars where the warranty has expired.

Insurance and tax

Electric cars have often insured higher, driven by repair complexity, parts cost, battery replacement risk and a smaller repair network. The gap has been narrowing as volumes rise, but it should be quoted rather than assumed — get real quotes for both specific cars before deciding, because the difference can offset a year of energy savings.

Tax treatment is the most jurisdiction-specific line and frequently the largest single incentive. Purchase grants, reduced registration tax, exemption from road tax, favourable company-car benefit rates, and exemption from congestion or low-emission zone charges all exist in various markets and change regularly. Company-car tax in particular can make an electric car dramatically cheaper than an equivalent petrol one for an employee, to the point where it overwhelms every other line in the calculation.

Building the comparison

1. Pick your holding period honestly — three, five or eight years changes the answer, because depreciation front-loads and servicing savings accumulate.
2. Estimate residual value at the end of that period for both cars. Use actual current asking prices for that model at that age rather than a percentage rule.
3. Compute energy cost per mile using your real charging mix and your actual tariff, then multiply by your real annual mileage.
4. Add scheduled servicing from the published schedules, plus a tyre allowance reflecting the weight difference.
5. Get real insurance quotes for both, on your postcode and history.
6. Apply your jurisdiction's tax treatment, including any company-car position, which may dwarf everything above.

Where each option genuinely wins

Electric wins clearly for: home charging with off-peak tariff, moderate to high annual mileage, mostly predictable routes, company-car drivers in favourable tax regimes, and urban drivers facing emission-zone charges. It wins by a large margin when several of those coincide.

Petrol or hybrid still wins for: no home charging, very low annual mileage where energy savings never repay a price premium, frequent long unplanned journeys in areas with thin charging infrastructure, towing at weight, and buyers keeping a car well beyond the battery warranty who are averse to that repair risk.

A note on used electric buying

If you go used, insist on a battery state-of-health report rather than accepting range estimates from the dashboard. Confirm remaining battery warranty and whether it transfers to a second owner. Check the maximum charging rate the car supports, because an older car limited to a low rate will be slow at public chargers regardless of how fast the charger is. And verify which charging standard it uses, since older standards are being decommissioned in some markets.

Charging at home: the one-off cost

A dedicated home charge point is the investment that makes the electric case work, and it is a modest one-off relative to the running-cost difference. The variables are cable run length from the consumer unit, whether the supply needs upgrading, and whether load management is required so the charger throttles when household demand peaks. Get two quotes, confirm the installer is certified for the scheme if a grant applies, and confirm the unit supports the off-peak scheduling your tariff requires — a smart charger that cannot be told when to draw power wastes the cheapest part of the case.

Leasing, PCP and the depreciation question

Because depreciation is the dominant and least predictable line, contracts that transfer residual-value risk to someone else are more attractive for electric cars than they usually are. A lease or a personal contract purchase with a guaranteed future value hands the residual risk to the finance company. If used electric values fall further, that is their problem; if they rise, you have overpaid modestly. For a market in rapid technical change, paying a premium to not own the residual is a defensible trade rather than a bad deal.

This is general information, not professional advice. Costs, cover, rates and rules vary by provider and location and change over time. Confirm current details directly with providers before deciding.