The economics work out where they’re pretty low-frequency (I think less than two an hour per direction is the usual figure).

They’re also useful as a transition technology. The DART+ project in Ireland will use them for one line which will have the frequency for electrification (8 trains per direction per hour) and is already partially electrified, but is going to take a while to fully electrify (due to low bridges etc); once it’s electrified they’ll then likely be used in low-frequency regional routes.

(The realised project will use 750 uniform cars, about 200 of which will have batteries.)