Bronze to Platinum, by battery-electric share.
Your tier is the battery-electric share of total fleet distance over the reporting period, calculated from the same distance sources as your tonnage. Plug-in hybrids count at their electric-mode share only. Every tier is displayed with the words "self-assessed" attached.
You have measured the fleet against the published method and issued a certificate anyone can check. Most fleets start here.
A fifth of your fleet distance is battery electric over the reporting period.
Two fifths of your fleet distance is battery electric. Plug-in hybrids count at their electric-mode share only.
Three fifths of your fleet distance is battery electric — and the grid electricity behind it is counted, not treated as zero.
A tier is not a reduction claim
Reaching Gold says what your fleet looks like today. It says nothing about last year. Year-on-year change appears on your certificate only once a snapshot around twelve months old exists to compute it from — until then it reads "Baseline is building".