Old cars and the Sunk-Cost trap

No one likes throwing stuff away. Trips to the ‘dump’ to add to the mountains of waste fill us with dread. That is a perfectly natural reaction, especially when what we are throwing away often fits into the category of ‘perfectly good’. It’s this that forms the foundation of the commonly held thinking behind wanting to keep hold of an old Internal Combustion Engine (ICE) car as its ‘more environmentally friendly to keep it going rather than to buy a new car’.

But is it? Are we doing anyone except oil companies a favour when we try and get a few more years out of a gas guzzler?

To be more objective we need to work with some assumptions, for this I have used the most commonly found results from the top of Google and stats from the office for national statistics – I’ve listed those at the end.

The usual line of thinking seems to be that you take your car of today (with no embodied carbon attached) and compare it with a brand-new EV.

Doing so today produces a 20-year chart like the below:

This shows six to seven years before reaching CO2 ‘breakeven’ point.

But is it really fair? If we are to make a similar blanket judgement about a ‘second-hand’ EV in the same way (reducing its embodied carbon to zero the day after it rolls of the forecourt) then we see this:

As can be seen the EV has a much lower contribution to atmospheric CO2 in comparison to the ICE car in this scenario, and that is achieved from the get-go.

For additional context this is new Vs new. In which case the carbon breakeven is around two and a half years.

The takeaway from this is that a simple comparison isn’t possible, but the carbon payback for the average UK driver is somewhere between the moment you start driving up to seven years depending on the mental gymnastics you choose.

In conclusion, the best time to go electric was probably two decades ago, but in the absence of time machines the best time is now, the main beneficiaries of delay are those that sell oil based fuels. From an environmental point of view retaining a fossil fuel powered car is type of sunk-cost fallacy. – the phenomenon whereby a person is reluctant to abandon a strategy or course of action because they have invested heavily in it, even when it is clear that abandonment would be more beneficial.

The overall takeaway (if you can’t mange without your own transport for whatever reason) is that a new small EV looked after for long time (yes the batteries are far more robust than many people think and constantly improving) is the best bet.

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Caveats:

• Walking, cycling and using public transport beat driving hands down from an environmental perspective.
• Better planned towns and cities would help trips be avoided.
• Car sharing is a great idea that reduces all sorts of environmental costs, and hopefully it will take off one of these days.
• The lifetime emissions from a small car (EV or ICE) are dramatically lower than those of a large car.
• There are clearly resource costs that go beyond CO2 emissions, and that’s rightly the subject of attention. However those costs do not present the existential risk to life that the continued burning of fossil fuels do.
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Notes:

• The average age of a car in the UK at scrappage is just 14 years old.
• Average milage is 7,000 per year, suggesting 98,000 miles at scrappage.
• Even the worst EV battery guarantees are 8 years/100,000 miles.
• Fewer than 0.5% of EV’s since 2016 have had battery replacements, that figure falls years on year.
• The higher your annual milage is the faster that payback will be thanks to greater fossil fuel avoidance.
• The second-hand market for EV’s is now mature and models can be found at most price points.
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Assumptions:

• UK electrical grid CO2 intensity of 160g per kWh (expected to drop to Ca.100g per kWh by 2030).
• EV efficiency 4 miles per kWh, resulting in 40g CO2 per mile driving electric.
• Typical UK car emits 220g CO2 per mile.
• 7,000 miles annual milage.
• 1.54 tons CO2 to drive a typical car 7,000 miles per year and 240kgs for the same milage charged from the National Grid at current grid intensity.