u/honestrangeuk

Been down a bit of a rabbit hole comparing EV tariffs after getting fed up with my standard rate thought I’d share what I found because the difference is actually pretty massive, you know.

The cheapest off-peak rates I’ve found so far

EDF GoElectric: 6.99p/kWh, 11pm–6am. Cheapest I’ve seen. No smart charger needed, just set a timer. The catch is the daytime rate is a bit higher.

Intelligent Octopus Go: around 8p/kWh, 11:30pm–5:30am + extra smart slots. You need a compatible charger or EV, but the smart charging is actually pretty handy.

E.ON Next Drive Smart: around 8p/kWh, midnight–6am + smart slots. Quite similar to Octopus, just starts at midnight.

Good Energy EV Charge: around 8p/kWh, midnight–5am. Shorter window, but 100% renewable.

E.ON Next Drive: around 9p/kWh, midnight–6am. Pretty simple, no smart charger needed.

British Gas EV Power: around 9p/kWh, midnight–5am. Another simple option.

OVO Charge Anytime: flat monthly fee of around £27.50–£37.50 for unlimited off-peak charging could actually work out quite well if you do a lot of miles.

The differences are actually quite big, you know, so it’s definitely worth checking what works best for how much you drive.

So what does that actually mean in money?

For a typical 60 kWh battery, like an Ioniq 5 or Model 3 LR:

Cheap tariff (7–9p/kWh): around £4–£5.50 for a full charge

Standard rate (24.5p/kWh): around £14.70

Public rapid (79p/kWh): £47+

Over 10,000 miles at 3.5 mi/kWh, that’s roughly £200 a year on a cheap tariff, compared with £700 on standard rate or around £2,250 using public rapid chargers alone.

Simple or smart tariff which one actually makes sense?

If you’ve just got a basic charger or granny cable, a simple tariff like EDF, E.ON Next Drive or British Gas is probably the easiest. Just set a timer and forget about it.

If you’ve got an Ohme, Indra, Hypervolt or a car with smart charging, then the smart tariffs like Octopus or E.ON Smart are probably worth a look. They can sort of move your charging around automatically and grab the cheaper slots.

I’ve put together a more detailed breakdown of the tariffs, off-peak times and requirements here:
https://honestrange.co.uk/guides/ev-tariffs-compared

What’s everyone else using? I’m quite curious about OVO’s flat-rate model it could actually be brilliant if you do loads of miles, but maybe not so much if you don’t.

I have recently published a paper that examines a commonly overlooked aspect in electric vehicle (EV) energy studies: the significant variation in energy consumption across different drive cycles.
A common explanation is that aerodynamic drag increases with speed. While this is accurate regarding the external forces on the vehicle, it does not address the processes occurring within the powertrain.

As motor speed increases, the electric motor moves between two operating regimes: maximum torque per ampere (MTPA) at lower speeds and field weakening at higher speeds. Field weakening keeps the motor within its voltage limits, but it comes with an efficiency penalty.
We used LMDI decomposition a method widely used in energy economics, but not previously applied at the powertrain level to break down the energy difference between drive cycles into two effects:

Structural effect: how much of the drive cycle is spent in each motor operating regime.
Intensity effect: how efficiently the motor operates within each regime.

A few key findings from the Tesla Model 3 and Chevrolet Bolt EV, validated to within 5% against dynamometer data across UDDS, HWFET, US06 and WLTP:

The structural effect dominates. For the Model 3, 78% of the 53 Wh/km difference between urban (UDDS) and aggressive highway (US06) driving comes from a larger share of motor operating points falling inside the field weakening region, not from the motor becoming less efficient at those operating points.

The Bolt enters field weakening at 88 km/h, while the Tesla holds off until around 118 km/h. This is despite the Bolt having a lower gear ratio.
Motor design parameters such as flux linkage, inductance and pole count appear to matter more than transmission gearing when it comes to how much real-world driving is spent in the less efficient regime.

How you define the regime boundary can change the result dramatically by up to 82 percentage points. Most studies don’t really discuss this modelling choice.
The practical takeaway is pretty interesting: when manufacturers choose motor parameters and gear ratios, they’re effectively deciding how much real-world driving will happen in the less efficient field-weakening region. You just don’t see that trade-off in a single Wh/km figure.

The paper is available as an open-access preprint here:
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=7212137
Happy to answer any questions about the methodology or results.

I have recently published a paper that examines a commonly overlooked aspect in electric vehicle (EV) energy studies: the significant variation in energy consumption across different drive cycles.
A common explanation is that aerodynamic drag increases with speed. While this is accurate regarding the external forces on the vehicle, it does not address the processes occurring within the powertrain.

As motor speed increases, the electric motor moves between two operating regimes: maximum torque per ampere (MTPA) at lower speeds and field weakening at higher speeds. Field weakening keeps the motor within its voltage limits, but it comes with an efficiency penalty.
We used LMDI decomposition a method widely used in energy economics, but not previously applied at the powertrain level to break down the energy difference between drive cycles into two effects:

Structural effect: how much of the drive cycle is spent in each motor operating regime.
Intensity effect: how efficiently the motor operates within each regime.

A few key findings from the Tesla Model 3 and Chevrolet Bolt EV, validated to within 5% against dynamometer data across UDDS, HWFET, US06 and WLTP:

The structural effect dominates. For the Model 3, 78% of the 53 Wh/km difference between urban (UDDS) and aggressive highway (US06) driving comes from a larger share of motor operating points falling inside the field weakening region, not from the motor becoming less efficient at those operating points.

The Bolt enters field weakening at 88 km/h, while the Tesla holds off until around 118 km/h. This is despite the Bolt having a lower gear ratio.
Motor design parameters such as flux linkage, inductance and pole count appear to matter more than transmission gearing when it comes to how much real-world driving is spent in the less efficient regime.

How you define the regime boundary can change the result dramatically by up to 82 percentage points. Most studies don’t really discuss this modelling choice.
The practical takeaway is pretty interesting: when manufacturers choose motor parameters and gear ratios, they’re effectively deciding how much real-world driving will happen in the less efficient field-weakening region. You just don’t see that trade-off in a single Wh/km figure.

The paper is available as an open-access preprint here:
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=7212137
Happy to answer any questions about the methodology or results.

I research battery electric vehicles, and rather than simply reducing the WLTP figure by a set percentage, I created a model that estimates real-world range for each car. It takes into account the actual drag coefficient, kerb weight, rolling resistance, battery chemistry, and heater type.
A few things that stood out:

Kia e-Niro / Hyundai Kona Electric:heat-pump cars lose noticeably less range in winter than PTC-only heaters. The heating system makes a bigger difference than most people realise.

Tesla Model 3 LR:still manages 200+ miles at 70 mph in winter. Efficient cabin heating and low drag make a big difference.

Nissan Leaf / Renault Zoe:some of the biggest drops at sustained motorway speeds in cold weather, around 35–45% below WLTP. PTC heating and higher drag really hurt.

Dacia Spring:loses the least in absolute miles, but proportionally it’s one of the hardest hit. Small battery and relatively high drag for its size don’t help.

VW ID.3 / BMW i3:somewhere around the middle, but the gap between them is bigger than you’d expect given their similar battery sizes.

I’ve put the full table together with every model at motorway (70 mph, 10°C), mild (50 mph, 15°C) and winter (55 mph, 2°C) conditions. Full data
I’ve also documented the methodology if anyone wants to pick it apart
Happy to answer questions or hear suggestions for models I should add.

I'm a BEV researcher at UEL and I've been building a physics model that estimates real range from each car's drag, mass, rolling resistance and heater type instead of trusting the WLTP number.
Some findings that surprised me:
Motorway range (70 mph, 5°C) can be 35-45% below WLTP on some models
Cars with heat pumps (Kia e-Niro, Hyundai Kona) hold up much better in winter than PTC heaters (older Leaf, Zoe)
The Dacia Spring loses the least in absolute terms but proportionally it's one of the worst
Tesla Model 3 LR still does 200+ miles in winter thanks to efficient cabin heating
Full breakdown with every model here: https://honestrange.co.uk/data/real-vs-wltp-range-gap
Happy to answer questions about the methodology. Everything is open and documented.