The FTSE 250-listed transport company has set out “not to buy another diesel bus in the UK” and to become the sector’s most sustainable player.
It also has operations in five other countries worldwide.
"There is scope for government funding to mitigate the additional capex, which should moderate over time anyway and which ought to be manageable in a group context," analysts at Liberum commented.
"The move should also head off moves towards re-regulation in the group’s operating regions."
In a separate announcement, National Express posted a “record set” of results for the year to 31 December, when it became Morocco’s “largest urban bus operator”.
Profit before tax jumped 9% to £240mln from revenue up 10% to £2.7bn.
The final dividend was raised 9% to 11.19p per share.
Shares dipped 1% to 407.2p on Thursday at the opening bell.
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