As far as the trains are concerned there is no visual evidence of diesel engines on close inspection and the noise vibration and exhaust fumes normally associated with diesels are absent to the extent that the First ScotRail ticket collector on the train today was convinced that they are electric trains though he did say that there are some noisy diesels running out of Central on some other routes If they are diesels putting such engines in the buses would make the streets a lot quieter Please WP CITE sources for your interesting revelation