The Cost of the Half Measure
When does the ‘sensible’ route become an expensive detour?
The ZEV Mandate. Regardless of recent uncertainty over whether the goal posts are moved or not, most local authorities have already made the big decisions, and they’re no longer up for debate. Whether the target is 2030, 2032 or 2035, most councils across the UK have committed to decarbonising their fleets.
Now comes the challenging part. How does fleet management keep the plates of procurement timings, budgets and operational requirements spinning while striving to achieve those targets?
For many authorities, the immediate answer is an understandable one. Plug-in hybrids, HVO and other transitional technologies offer a practical way of reducing emissions without forcing operational change overnight. They allow fleets to continue delivering essential services while infrastructure catches up, funding becomes available and battery-electric technology matures across every vehicle category. And, one could argue, there’s nothing inherently wrong with that approach.
But are those interim decisions are genuinely bridging the gap, or are they or simply delaying decisions that still must be made?
The Cost of Buying Time
Take the replacement cycle. Before Covid, replacement cycles of three to five years were common across many larger fleets. Supply-chain disruption, inflation and continuing budget pressures have since encouraged many operators to keep vehicles in service for considerably longer. Six-, seven- and even eight-year replacement cycles are becoming increasingly familiar as authorities seek to extract more value from existing assets. Buy a vehicle today and there's every chance it will still be earning its keep well into the period when the council expects its fleet to be substantially, if not entirely, zero emission. It is our understanding that, as a result, the procurement process has, shall we say, ‘evolved’.
This is neither argument nor criticism against HVO or plug-in hybrids vehicles. Both have a legitimate place within the right duty cycle. A highways vehicle covering unpredictable distances, specialist plant with no viable electric alternative or a vehicle operating in areas where charging infrastructure simply doesn't yet exist may be entirely justified.
The difficulty starts when an interim solution becomes so entrenched in the process it becomes part of the long-term strategy. Unfortunately, buying HVO doesn't remove the need to electrify the depot; buying a plug-in hybrid doesn't eliminate the need to upgrade grid capacity; and extending the life of diesel vehicles certainly doesn't make charging infrastructure any less necessary if we are going to adhere to mandated targets. At some point, the existing fleet still must be disposed of.
There's another consideration. Neither plug-in hybrids nor HVO are the low-cost option they're sometimes perceived to be. HVO typically commands a premium over conventional diesel while delivering lower energy density, meaning more fuel is required to achieve the same work. Plug-in hybrids carry a higher purchase price than an equivalent diesel and, over their lifetime, still require fleets to maintain an internal combustion engine alongside an electric drivetrain. In other words, councils may be paying more today for technologies that still leave much of tomorrow's investment untouched.
The depot still needs electrifying. The grid connection still needs upgrading. Charging infrastructure still has to be designed, procured and installed. The operational transition hasn't disappeared simply because the vehicle has changed.
The Cost Nobody Budgets For
We believe that this is conversation local authorities should now be having. Fleet managers are already experts at calculating whole-life cost; now they need to make a second, and probably more significant in the long run, calculation - the cost of the transition itself.
That said, whole-life cost calculations also deserve a second look. It's true that battery-electric vehicles often demand a higher initial capital outlay, but purchase price tells only part of the story. Lower energy costs, reduced servicing requirements, fewer moving parts and lower maintenance overheads mean the financial picture often looks very different over the life of the asset. Judging an electric vehicle solely on acquisition cost risks comparing the most expensive day of ownership with every day that follows.
Charging infrastructure, depot upgrades, power supply, procurement, financing and vehicle replacement all influence one another. Delay one and the others rarely stand still. Construction costs don't pause; and grid connections don't become easier. Vehicles will continue to depreciate.
None of those investments become unnecessary because a council buys another generation of interim vehicles. They simply move further down the programme. In some cases, they may become more expensive. Grid connections are unlikely to become quicker. Construction costs rarely fall. Demand for charging infrastructure will only increase. Meanwhile, every year spent delaying the transition is another year in which ageing diesel assets continue to depreciate.
One assumption says the halfway house vehicles will remain in service long enough to justify the investment. Another assumes that legislation, infrastructure, funding and operational requirements won't overtake it first.
It’s important then, in that context, to understand that delaying a vehicle purchase doesn't necessarily delay the transition; it may simply separate one part of the cost from another.
The Residual Value Trap
Perhaps the greatest financial risk lies elsewhere. Diesel residual values have remained surprisingly resilient in recent years, supported by constrained supply. That position is unlikely to last indefinitely. As the market moves towards the end of new diesel sales and more operators begin disposing of legacy fleets, those values are expected to come under increasing pressure. Councils delaying replacement programmes could therefore find themselves caught twice: paying more for the vehicles that eventually replace the fleet while recovering significantly less from the assets they're disposing of. The transition becomes more expensive from both directions.
None of this suggests that every council should abandon interim technologies tomorrow morning. That would be as simplistic as claiming every fleet can switch entirely to battery-electric overnight. Reality is rarely that accommodating. Instead, perhaps each procurement decision needs to answer one additional question, "Does this purchase reduce the amount of transition we still have left to do?"
None of this suggests that every plug-in hybrid or HVO-powered vehicle is the wrong decision. For certain applications, they remain the right tool for the job. The danger comes when those decisions are repeated across a fleet simply because they feel like the least risky option.
Every procurement decision should move the fleet measurably closer to its end state. If it doesn't, the authority risks paying for today's compromise while still funding tomorrow's transition.
The greatest cost facing council fleets over the next decade may not be the price of buying battery-electric vehicles. It may be the cumulative cost of delaying the point at which the transition genuinely begins.
