There are some 80 million heavy trucks in the US, UK, and EU and they have a life time span with trucks regularly running for 1-2 million kilometres. They do however need regular engine rebuilds. The thesis of several startups is to provide rebuilds at the same cost as a normal engine rebuild, but to instead refurbish them as electric battery vehicles. This means that the existing fleet will be slowly replaced with clean vehicles even as new purchases move towards electric options.
The Fully Charged Show has a couple of great videos from
Janus in Australia and
Lunaz in the UK. This is a pretty interesting and exciting step change in the industry as it means smaller countries like New Zealand could start to take part in the transition of trucking to electric by importing kits for fitting onto the existing fleet.
And then there are the buses... coach builders here should be looking at the same possibilities.