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Even though the power cars can carry passengers, the Comet fails to meet the criteria of a DMU because only the power cars were powered, the middle car was not. A DMU has distributed traction, whereas the engines were concentrated ONLY in the power cars. While some railfan sites casually label it a “DMU,” this is imprecise. The Comet is more accurately a diesel‑electric articulated streamliner. ~2026-30142-57 (talk) 20:15, 19 May 2026 (UTC)[reply]

How is categorizing it as a locomotive, as you have, more accurate? Also, as the editor trying to overturn consensus the burden is on you to provide reliable sources that support your claim. XtraJovial (talk • contribs) 00:36, 20 May 2026 (UTC)[reply]

This is a weird edge case. It's reasonable to interpret it either as a DMU set with an unpowered middle car, or a streamliner trainset with power cars (ie locomotives with seating) at the ends. There were a number of early streamliners with configurations that don't quite match either conventional DMU or locomotive+coaches form factors; it may be that we need a separate category. I would recommend a wider discussion at WP Trains. Pi.1415926535 (talk) 14:05, 20 May 2026 (UTC)[reply]

Note that there isn't a simple clean division between a multiple unit and a (semi-)fixed rake of coaches with a locomotive. e.g. the Intercity 125 was classed as a DMU and as locos+coaches at different times. As ever though, it doesn't matter what we think a particular train should be described as, what matters is what reliable sources describe it as, even if that is contrary to conventional definitions. Thryduulf (talk) 15:32, 20 May 2026 (UTC)[reply]

Whether the centre car is powered or not is irrelevant. I can name several types of British DMU with one or more unpowered cars - Class 100, 103, 109, 115 (one powered car and one unpowered); Class 107, 110, 116, 117, 118, 119, 120, 125 (two powered cars flanking one unpowered); Class 115, 123, 127 (two powered flanking two unpowered) and this list is not exhaustive.

The main feature that distinguishes a multiple-unit is that there is one or more control cables running the whole length of the train, by means of which the cab at the leading end may control all of the powered vehicles in the train. --Redrose64 🌹 (talk) 17:28, 20 May 2026 (UTC)[reply]

This is definitely not a locomotive. Look at some definitions here:

• A Locomotive is a traction vehicle (or combination of several vehicles) that is not intended to carry a payload and has the ability to be uncoupled in normal operation from a train and to operate independently.
• A Trainset is a fixed formation that can operate as a train; it is by definition not intended to be reconfigured, except within a workshop environment. It is composed of only motored or of motored and non-motored vehicles.
• An Electric and/or Diesel Multiple Unit is a trainset in which all vehicles are capable of carrying a payload (passengers or luggage/mail or freight).

DMU is not necessary a power-distributed trainset or a trainset with all motorized cars, it can be a power-centralized trainset with one or two power cab cars that carries passengers or any payload (examples are DB Class VT 11.5, OSE class 520) or even a trainset with an intermediate power pack car (examples are Stadler Flirt and Stadler GTW DMUs). The term "multiple" means that this train consists of multiple cars (at least two) and this is not a standalone railcar or motor coach. It can consist of motor and trailer cars, and not necessary all of them should have their own diesel engines and traction motors (in case of DEMU). Even trainsets with locomotive-like power cars which does not carry passengers, such as TGV, Talgo, CR200J or HST are categorized on Wiki as EMUs and DMUs (this term is not entirely correct in English; a more accurate term is electric or diesel trainset, but their power cars are not classified as locomotives, since they cannot be operated separately with ordinary passenger coaches). https://www.google.ru/books/edition/Introduction_to_High_Speed_Railway/rTHaEAAAQBAJ?hl=ru&gbpv=1&pg=PA145&printsec=frontcover

In this case, we have a typical power-centralized DMU which is not a single railcar and not a locomotive. ~2026-30361-87 (talk) 21:46, 20 May 2026 (UTC)[reply]

Well... even though the power cars carried passengers, almost no one calls the Comet a DMU. While it technically fits the broadest modern definition of a DMU as it was a self-propelled passenger train with diesel engines, the term DMU is almost avoided because in the 30s, the railroad industry and the public used 'streamliner' to describe the then-new wave of sleek, lightweight, aerodynamic trains like this train, the Pioneer Zephyr, and Union Pacific's M-1000x series. Due to the cars sharing middle wheel trucks (they are articulated), they couldn't be uncoupled coupled, nor added like modern DMUs. These trains are instead classified as integrated trainsets rather than MUs. The Comet had two 400-hp Westinghouse inline-6 engines, one on each power car, allowing the train to run in either direction, making this train function more like a miniature, permanently attached top-and-tail locomotive-hauled trainset rather than a DMU with distributed traction. ~2026-30173-94 (talk) 13:05, 7 June 2026 (UTC)[reply]