Just how energy and cost efficient can an MG4 Urban be?

[River Mersey]

​

“Under what conditions can a privately owned electric vehicle charged on dynamic time‑of‑use tariffs achieve cost‑per‑mile efficiency comparable to or exceeding that of public bus transport?”

or:​

“How does optimised EV charging during renewable‑oversupply periods compare to the maximum theoretical cost‑efficiency of urban bus transport?”

or:​

“Does the assumption that public transport is always the most cost‑efficient mode of urban mobility hold when compared to an EV charged during renewable‑oversupply windows?”

Title​

Re‑evaluating Transport Efficiency: A Case Study Comparing Optimised EV Charging to Maximum‑Efficiency Public Bus Travel

Abstract​

Public transport is widely assumed to be the most cost‑efficient mode of urban mobility. This study challenges that assumption by comparing the real‑world cost‑per‑mile of a privately owned electric vehicle (EV) charged exclusively during low‑demand, renewable‑oversupply periods on a dynamic electricity tariff, with the maximum theoretical distance achievable using a Merseytravel Day Saver bus ticket. Over a 31‑day period, the EV achieved a cost of 3.2 pence per mile, comparable to the 3.1 pence per mile theoretical minimum achievable on Mersey buses when riding the longest route continuously for 18 hours. The findings suggest that under specific grid and behavioural conditions, private EV transport can match or exceed the cost‑efficiency of public transport, challenging conventional assumptions in transport economics.

1. Introduction​

Public transport is commonly regarded as the most efficient and sustainable mode of urban mobility. This assumption is embedded in transport policy, academic literature, and public discourse. However, the rapid growth of renewable energy, combined with dynamic electricity pricing, has created new opportunities for highly efficient private EV operation. This essay examines whether an EV charged strategically during renewable‑oversupply periods can rival or surpass the cost‑efficiency of public bus transport.

2. Methodology​

2.1 EV Charging Data Collection​

A single EV (MG4 Urban E3 Platform, FWD, Comfort) was monitored over a 31‑day period (4 May–4 June 2026). Charging occurred almost exclusively during low‑price windows on the Octopus Agile tariff, typically aligned with:

• midday solar peaks
• moderate wind generation
• mild‑temperature low‑demand periods
• occasional negative‑price events

Total energy delivered, cost, charging duration, and odometer readings were recorded.

2.2 Public Transport Benchmark​

To establish a fair comparison, the study does not use average bus journeys. Instead, it calculates the maximum theoretical distance a passenger could travel in one day using a Merseytravel Day Saver (£5.80).

The longest continuous Mersey bus route (Route 17) was selected:

• Approx. 22 miles per full cycle
• Approx. 1 hour 45 minutes per cycle
• Approx. 18 hours of daily service

This yields a maximum of 10 cycles per day, or 220 miles per Day Saver.

3. Results​

3.1 EV Efficiency​

Over the 31‑day period:

• Total distance travelled: 378 miles
• Total energy delivered: 95.35 kWh
• Total cost: £12.04
• Cost per mile: 3.2 pence
• Efficiency: 3.96 miles/kWh

3.2 Maximum Bus Efficiency​

Using the Day Saver:

• Maximum miles per day: 220 miles
• Cost per mile: 5.80 ÷ 220 = 2.6 pence per mile

To match the EV’s 378 miles:

• Days required: 1.72 days → 2 days
• Total cost: £11.60

Thus, the EV’s cost‑per‑mile is effectively equal to the absolute upper bound of bus efficiency.

4. Discussion​

The findings challenge the assumption that public transport is inherently the most efficient mode of travel. While buses remain more efficient under typical usage patterns, this case study demonstrates that:

• dynamic electricity pricing
• renewable‑oversupply windows
• user‑optimised charging behaviour

…can enable private EVs to achieve cost‑efficiency comparable to — or even exceeding — public transport.

This does not imply that EVs replace buses in terms of social equity, congestion reduction, or land use. However, it highlights that energy‑system dynamics can invert traditional transport‑efficiency hierarchies.

The result is particularly striking because the bus comparison uses a theoretical maximum that no typical passenger would ever achieve. Meanwhile, the EV’s efficiency is based on real behaviour, not an idealised model.

5. Limitations​

• Single‑vehicle case study
• One geographic region (Merseyside)
• One tariff (Octopus Agile)
• Weather‑dependent renewable generation
• Assumes perfect bus‑route cycling without delays

Despite these limitations, the analysis provides a compelling proof‑of‑concept.

6. Conclusion​

This study demonstrates that a strategically charged EV can match the maximum theoretical cost‑efficiency of public bus transport. As renewable penetration increases and dynamic tariffs become more common, the boundary between private and public transport efficiency may shift. Policymakers and transport planners should consider the implications of energy‑system behaviour on mobility economics.

 

[Anon70]

I guess with any study some assumptions have to be made but some minor tweaks to these would give different results.

For example:
The number of stops the bus makes and how long each stop takes (which would vary by the number of passenger getting on and off at each stop)

The capacity of the bus vs the car, if you fully load the bus you are looking at multiplying the passenger miles covered by a factor of 50 or more, where the car can take a maximum of 5 occupants

 

[River Mersey]

You’re absolutely right that passenger‑capacity changes the total system efficiency — a fully loaded bus spreads its energy and cost across many people. But this study isn’t comparing system‑level efficiency.

It’s comparing cost‑per‑mile for a single traveller, because that’s the metric that matters when an individual decides:

“Should I take the bus today, or should I drive my EV?”

In other words: If I travel 10 miles on a bus, I pay £2. If I travel 10 miles in my EV, I pay ~32p. The fact the bus could carry 50 people doesn’t change what I pay. So the comparison is intentionally framed around:

maximum miles a single person can physically travel on a Day Saver,
versus actual miles I travelled in my EV,
charged only during renewable‑oversupply windows.

It’s a user‑level comparison, not a network‑level one.

Both perspectives are valid — they just answer different questions.

 

[Bam Bam]

Is this about energy efficiency overall, or cost to the commuter?

If it is about cost then parking is the big difference. In Oxford the park and ride is cheap (drive and then get a bus) but parking in the City centre is prohibitively expensive. I imagine it would be the same in Liverpool, if that is where you are going.

In terms of time, trains run on a timetable and don't get caught in traffic.

Electric buses, trams and trains seem to be the ideal for big cities!

 

[River Mersey]

My commute doesn't include parking costs at either end - I park in company car park for free

Parking costs aren’t relevant to this study because the comparison is based on cost‑per‑mile for a single traveller. Parking is a destination‑based cost, not a distance‑based one, and it varies so widely between individuals that it doesn’t form part of a fair cost‑per‑mile comparison.The study is specifically about the cost of movement — maximum miles per £ on a Day Saver versus actual miles per £ in an EV charged during renewable‑oversupply windows

 

[MG Clive]

But surely if this question/decision is about finding the cheapest journey cost, then the overall cost, including destination parking must be considered.

“Should I take the bus today, or should I drive my EV?”

 

[River Mersey]

As said, for me, parking isn’t a concern — either for parking the MG4 or for parking when using the bus.

My essay was comparing the cost of using over‑production electricity to drive an EV versus the cost of travelling the equivalent miles by bus.

Parking costs aren’t part of this analysis because the essay isn’t comparing the cost of visiting destinations. It’s comparing the cost of moving miles.

Parking is a destination‑based cost, not a distance‑based one, and it applies equally to any mode of transport.The study is specifically about the cost of using surplus renewable electricity to travel a given number of miles in an EV, versus the cost of travelling the same number of miles using a Day Saver bus ticket.

As such, parking doesn’t enter into the cost‑per‑mile calculation for either mode.

By adding parking, I’d also have to add the bus equivalent (extra fares, walking time, connections, etc.), which would move the study away from cost‑per‑mile and into behavioural travel modelling — a completely different topic.

Simply put, the comparison is between what it costs a bus traveller to cover a certain number of miles and what it costs the MG4 Urban to travel roughly the same number of miles using surplus renewable electricity — a straightforward cost‑per‑mile comparison.

 

[Anon70]

I can understand that the scope of the essay has certain parameters but this is where you can see headlines that never explain the parameters of a study just the outcome.

You are comparing the cost of the bus fare against the cost of the EV energy. In theory a like for like comparison would be the cost of the bus fuel against the cost of the EV fuel as the fares may be regulated or restricted in some way. For example in Scotland anyone over 60 or under 22 can travel on buses for free.