Daisy is a Diesel Railcar
Daisy is a diesel railcar, who has been known to consider herself "highly sprung and right up to date". She was brought to help run passenger services on Thomas' Branch Line, while Thomas was "indisposed" after running into the stationmaster's house. She can be hard to please, mostly indignant, and highly opinionated. She is extremely authoritative, trustworthy, and confident in herself and can sometimes boast of her abilities in particular situations, unconcerned, despite having never actually been in such a position before. She will sometimes presume she can show other engines a thing or two, despite knowing little on the matter, until she actually learns for herself.
After arriving on Sodor, Daisy insisted that she required delicate handling and considered pulling trucks and vans to be below her. She was very lazy and stubborn, but the Fat Controller spoke severely to her, telling her that his engines must work hard and that he sends lazy engines away. However, the Fat Controller felt she deserved another chance after she worked hard clearing up after an accident Percy had. Daisy is now good friends with the other engines on Thomas' Branch Line, tries to work much harder to be a Really Useful Engine and is better capable of handling things alone. Daisy can be described as a self-obsessed diva and also vain about not wanting her interior be dirty one bit.
Despite changing for the better, Daisy is still snarky and irritable. During the steam engines’ feud with the diesels, she temporarily sided with the diesels in their campaign to get rid of all of the steam engines.
In newer episodes, Daisy was heard speaking French, such as when she said "Merci beaucoup" (Thank you very much) to Den and Dart after she was repaired, and when she used the terms to describe the entertainers she was to carry to Duck and Oliver, which indicates that she has knowledge in the French language as well.
Daisy is based on the BR/Metro-Cammell Class 101/102 DMU. She is, however, a single railcar instead of the traditional two to four-piece units. These were one of the longest serving class of "First Generation" DMUs, with its service life of 47 years only being replaced by the Class 121. A total of 41 cars are preserved. A preserved Class 101 set (#101680) appeared on a Mr. Perkins' Railway segment.