Complex sentence: Vehicles were to operate on 750 V DC and 25 kV AC electrification systems, and be able to brake using regenerative braking, maintenance time was to be reduced by modular components, remote diagnostics, and avoidance of overly complicated systems.
Split into simpler sentences: Vehicles were to operate on 750 V DC and 25 kV AC electrification systems, with regenerative brakes. Maintenance time was to be reduced by the use of modular components, remote diagnostics, and the avoidance of over-complicated systems.