Electric vehicles
Charging a plug-in hybrid at home: cost per mile on 7.6p vs petrol
Last checked: 15 October 2026 · SmartShift UK
A plug-in hybrid has a small battery for electric miles and a petrol engine for the rest. Whether plugging in at home is worth it comes down to pence per mile on electricity against pence per mile on petrol. This page works both out, with every assumption labelled.
Electric miles: pence per mile
PHEVs aren’t in the site’s 142-car table, which only covers battery-electric cars. So this page uses 3.0 miles per kWh as a labelled example, not a measured figure for any model. Your car’s trip computer or handbook gives your own.
- At 7.6p off-peak: 7.6 ÷ 3.0 = 2.5p a mile.
- At the 26.32p price cap: 26.32 ÷ 3.0 = 8.8p a mile.
- Pence per mile = rate ÷ miles per kWh, so at 2.5 mi/kWh it would be 3.0p and 10.5p; at 3.5 mi/kWh, 2.2p and 7.5p.
Petrol miles: pence per mile
The UK average pump price for unleaded petrol was 175.28p a litre in the week of 12 October 2026, from the government’s weekly road fuel prices. A UK gallon is 4.54609 litres, so pence per mile = 175.28 × 4.54609 ÷ mpg.
| Petrol mpg (example) | Pence per mile | vs 7.6p electric | vs 26.32p electric |
|---|---|---|---|
| 30 mpg | 26.6p | 24.0p cheaper on electric | 17.8p cheaper on electric |
| 40 mpg | 19.9p | 17.4p cheaper on electric | 11.1p cheaper on electric |
| 50 mpg | 15.9p | 13.4p cheaper on electric | 7.2p cheaper on electric |
| 60 mpg | 13.3p | 10.7p cheaper on electric | 4.5p cheaper on electric |
The mpg values are examples to show the range; a PHEV’s petrol-only mpg once the battery is empty is what matters, and the official combined figure includes electric miles, so it will look much higher.
A year of short trips
The homepage calculator has a “2,000 mi (City/PHEV)” marker. At 3.0 mi/kWh, 2,000 electric miles is 667 kWh: £51 at 7.6p or £175 at 26.32p. The same 2,000 miles on petrol at 40 mpg is 227 litres, about £398.
Will a granny lead fill it overnight?
A 2.3 kW three-pin lead adds 13.8 kWh in the six hours from 23:30 to 05:30, before losses. If your PHEV’s usable battery is smaller than that, it can be filled from empty in one window. Check the usable figure in the handbook (it is less than the gross battery size) and the car’s maximum AC charging power, which can be lower than a wallbox delivers. Safety advice for 3-pin charging is in granny charger vs wallbox.
Short trips vs long trips
- Short, regular trips that fit inside the electric range get the full pence-per-mile saving every day you plug in.
- On long trips, once the battery is empty, the car runs on petrol and the saving stops. A PHEV running on petrol is also carrying the weight of its battery.
- Some EV tariffs are only for battery-electric cars, and some accept plug-in hybrids. Ecotricity’s EV tariff page, for example, says it was open to electric or hybrid vehicles (though it was unavailable on 15 October 2026). Check the supplier’s eligibility for a PHEV before you switch. Rates are in UK EV tariffs compared.
Questions people ask
How much does it cost to charge a plug-in hybrid at home?
Energy × rate. At an example 3.0 miles per kWh, an electric mile costs about 2.5p at 7.6p off-peak and 8.8p at the 26.32p price cap. A 10 kWh top-up would cost 76p off-peak or £2.63 at the cap, before losses.
Is it cheaper to run a PHEV on electric or petrol?
With petrol at 175.28p a litre (UK average, week of 12 October 2026), a 40 mpg car costs about 19.9p a mile, against 2.5p off-peak or 8.8p at the cap for the 3.0 mi/kWh example. Electric is cheaper in both cases.
Can I get an EV tariff with a plug-in hybrid?
Some suppliers accept PHEVs and some only battery-electric cars. Check eligibility on the supplier’s own page before you switch.
Is this financial advice?
No. The 3.0 mi/kWh and mpg values are labelled examples. Use your own car’s figures.
Not financial advice. These are worked examples from published rates and EV-Database consumption estimates, for planning only. Your own tariff, day rate, standing charge, car, driving and weather will change the numbers. Check your bill and your supplier’s current terms before you switch or buy anything.
Sources
- GOV.UK (DESNZ), weekly road fuel prices, week of 12 October 2026
- Octopus Energy, Intelligent Octopus Go (checked 15 October 2026)
- Ofgem, energy price cap unit rates and standing charges (1 October–31 December 2026)
- Ecotricity, EV tariff (eligibility wording)
- SmartShift UK, UK EV tariffs compared (checked 15 October 2026)
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