Fleet running costs

The single figure THRIVE publishes on running cost is the Fleet Cost Index: how many times more expensive a diesel van is to fuel, per mile, than an electric one. It is recomputed every Tuesday from official data. The diesel side takes the Department for Energy Security and Net Zero's weekly average UK diesel price, multiplies by 4.54609 litres to the gallon and divides by a documented representative diesel van economy of 36mpg. In the week ending 21 September 2026, with diesel at 195.53p a litre, that gave 24.69p a mile.

The electric side uses HMRC's advisory electric rates, which have had a separate public charging figure since 1 September 2025: 7p a mile for home charging and 15p on the public network. Blended on a stated home-charging share, that put the index at 2.63 in the latest week, up from 2.56 the week before as diesel rose 4.81p a litre. The index moves with the pump price; the electric rates move only when HMRC resets them each quarter.

The gap between 7p and 15p is the biggest lever a fleet controls. A driver who can plug in at a depot or at home runs at less than half the per-mile cost of one who relies on the public network, before any difference in the vehicles themselves. The cost to charge and charging cost gap pages set out those figures, and the electric van break-even page turns them into the annual mileage at which an electric van pays back its price premium.

Fuel is not the whole bill. Company car tax, mileage reimbursement, HGV testing and operator licence fees each have their own THRIVE dataset, every one sourced to the official document it comes from and re-checked on a schedule. The topic guides linked below collect the stories and the data on each.