Some diesel cars are 24 volts:
A lot of diesel powered pick-ups are also 24 volts:
All big diesel rigs {18 wheelers} are 24 volts:
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Now when I say 24 volts that is their starting systems. Most of the rest of the electrics is {lights, radios etc} 12 volts on the newer ones. Older ones had full 24 volts systems.