Methodology: how these numbers are calculated
These comparisons use consistent assumptions applied across all three mileage scenarios. Understanding the methodology lets you adjust the figures for your own situation.
EV efficiency: 3.5 miles per kWh. This is a realistic average for a typical UK electric family car (equivalent to a Tesla Model 3, Volkswagen ID.4, or Hyundai Ioniq 6) in mixed driving conditions. More efficient EVs (smaller cars, mostly city driving) may achieve 4-5 miles/kWh. Less efficient ones (large SUVs, motorway-heavy driving) may achieve 3 miles/kWh.
Charging split: 80% home charging, 20% public charging. This reflects the pattern for most EV owners with a home charger. If you rely more heavily on public charging, apply the public charging rate to the higher percentage.
Agile overnight home rate: 4p/kWh average. This is a conservative estimate for consistent overnight Agile charging between 12am and 6am. Many nights are cheaper than this. Plunge pricing events bring the blended average down further for drivers who capture them.
Price cap home rate: 26.11p/kWh. This is the Ofgem price cap unit rate for July 2026. Standard variable tariff and fixed tariff customers pay at or close to this rate for home electricity.
Public charging rate: 35p/kWh average. This reflects the midpoint of typical UK public charger pricing in 2026: faster AC chargers around 30-35p, rapid DC chargers 45-65p, slower chargers 25-30p. The blended figure for a typical driver's public charging mix.
Petrol comparison: 35mpg vehicle at 140p per litre (£1.40). This represents a reasonably fuel-efficient petrol family car (e.g., a Ford Focus or Toyota Corolla) at June 2026 average UK pump prices.
All figures are for fuel/electricity costs only. They exclude depreciation, insurance, servicing, and road tax, which vary by vehicle and driver profile.
8,000 miles per year: the lower-mileage driver
At 8,000 miles per year and 3.5 miles/kWh efficiency, you use 2,286 kWh annually for charging. The 80/20 split gives 1,829 kWh of home charging and 457 kWh of public charging.
On Agile overnight rates: home charging costs £73 (1,829 kWh at 4p). Public charging costs £160 (457 kWh at 35p). Total annual EV charging cost: £233.
On the standard price cap: home charging costs £478 (1,829 kWh at 26.11p). Public charging costs £160 (unchanged). Total: £638.
The petrol equivalent: 8,000 miles at 35mpg requires 228 gallons, or 1,040 litres. At 140p/litre, that's £1,456 per year in fuel.
Agile saves £405 per year versus the price cap, and £1,223 per year versus petrol, even at a relatively modest mileage. The Agile advantage is smallest at this mileage band but still substantial in absolute terms.
12,000 miles per year: the UK average driver
12,000 miles is close to the UK average annual mileage. At 3.5 miles/kWh, this requires 3,429 kWh of total charging. The 80/20 split produces 2,743 kWh of home charging and 686 kWh of public charging.
On Agile: home charging costs £110 (2,743 kWh at 4p). Public charging costs £240 (686 kWh at 35p). Total: £350 per year.
On the price cap: home charging costs £716 (2,743 kWh at 26.11p). Public charging costs £240. Total: £956 per year.
Petrol equivalent: 12,000 miles at 35mpg requires 341 gallons or 1,559 litres. At 140p/litre: £2,183 per year.
Agile saves £606 per year versus the price cap. That's £50 per month in your pocket simply from choosing the right tariff. Versus petrol, the Agile EV driver saves £1,833 annually. For the average UK driver, switching to an EV on Agile saves more than the cost of a typical family holiday every year.
20,000 miles per year: commuters and high-mileage drivers
High-mileage drivers see the most dramatic savings. At 20,000 miles and 3.5 miles/kWh, you need 5,714 kWh annually. The 80/20 split: 4,571 kWh home, 1,143 kWh public.
On Agile: home charging costs £183 (4,571 kWh at 4p). Public charging costs £400 (1,143 kWh at 35p). Total: £583 per year.
On the price cap: home charging costs £1,193 (4,571 kWh at 26.11p). Public charging costs £400. Total: £1,593 per year.
Petrol equivalent: 20,000 miles at 35mpg requires 572 gallons or 2,600 litres. At 140p/litre: £3,640 per year.
Agile saves £1,010 per year versus the price cap. That's a meaningful four-figure annual saving from tariff choice alone. Versus petrol, the saving is £3,057 per year. Over five years of high-mileage driving, Agile EV ownership saves over £15,000 in fuel costs compared to petrol.
The full comparison table
| Mileage | EV on Agile | EV on Price Cap | Petrol 35mpg | Agile vs Petrol |
|---|---|---|---|---|
| 8,000 miles/yr | £233 | £638 | £1,456 | Save £1,223 |
| 12,000 miles/yr | £350 | £956 | £2,183 | Save £1,833 |
| 20,000 miles/yr | £583 | £1,593 | £3,640 | Save £3,057 |
Assumptions: 3.5 miles/kWh efficiency; 80% home charging, 20% public at 35p/kWh; Agile home rate 4p/kWh average; price cap rate 26.11p/kWh (July 2026); petrol at 140p/litre. Fuel and electricity costs only.
Adding public charging reality: the blended cost
The figures above use a 80/20 home-to-public split. Some drivers, particularly those without a home charger or who travel frequently, use public charging for a much higher proportion of their charging needs. Here's how increasing public charging use affects the Agile advantage.
At 40% public charging (common for urban flat-dwellers or regular long-distance drivers), the picture changes for the 12,000-mile driver. Home charging: 2,057 kWh. Public charging: 1,371 kWh. Agile cost: £82 home + £480 public = £562 total. Price cap cost: £537 home + £480 public = £1,017 total. Petrol: £2,183.
Even at 40% public charging, Agile still saves £455 versus the price cap and £1,621 versus petrol for 12,000 miles. The Agile advantage on home charging is diluted by high public charging use, but not eliminated. And the EV versus petrol saving remains compelling at every mileage band regardless of public charging mix.
The key insight: if you can access home charging, even occasionally, the Agile advantage is worth pursuing. And if you're currently on a standard tariff charging your EV at home, switching to Agile is the single highest-ROI change you can make to your energy setup.
Payback on switching to Agile: how quickly does it pay off?
The switch to Agile has no upfront cost in itself. Switching energy supplier is free. You need a smart meter (which Octopus installs for free). If you already have a smart meter on another supplier, the switch takes about two weeks and costs nothing.
For a 12,000-mile EV driver currently on a standard tariff, switching to Agile saves approximately £606 per year on EV charging alone. The saving starts from the first month. Payback on switching is literally immediate.
If you also invest in a smart home charger to maximise Agile optimisation, say an OHME at £900 installed, the charger pays itself back within two years (at £606/year in Agile EV savings on top of what a basic timed charger would deliver). For high-mileage drivers, payback can be under 18 months.
The question is not whether switching to Agile is worth it for EV owners. The question is why any EV owner with a home charger has not already switched. See tonight's live Agile prices to understand the opportunity you might currently be missing every single night.