Stadler FLIRT

Updated: August 2026 – Hardly any vehicle shapes German regional services as strongly as the Stadler FLIRT. It runs for numerous operators – from eurobahn to the subsidiaries of large groups – in almost every conceivable livery and under several class numbers. This page shows you how to identify it regardless of its colours, what the numbers 427, 428 and 429 actually mean and where the line runs between it and similar competing products.

What is the Stadler FLIRT?

The FLIRT is an articulated electric multiple unit for regional services, built by Stadler. The name stands for Flinker Leichter Innovativer Regional-Triebzug (nimble, light, innovative regional multiple unit) and refers to a product family, not a single class. That is precisely the most important point for identification: FLIRT is the manufacturer’s name, 427 to 429 are the German class numbers.

Technically, the FLIRT is an articulated train: the cars rest on shared Jacobs bogies instead of each car getting two bogies of its own. That saves weight, shortens the train for the same capacity and gives a very characteristic view of the underframe – namely one bogie more than there are cars.

For once, the class number tells you something

German class numbers are usually purely administrative numbers. The FLIRT classes are different: they follow the number of cars.

Class	Cars	Bogies	Typical use
427	three	four	shorter regional lines, lower demand
428	four	five	the standard case in regional services
429	five	six	busy Regional Express lines
extended numbers (e.g. 1428, 3428)	as base class	as base class	later batches of the same family

Class 427 is thus the three-car unit and Class 429 the five-car unit. Prefixed digits, as on a 1428 or 3428, merely extend the number range because the classic three-digit blocks were no longer sufficient – nothing fundamental about the design changes as a result.

How to identify a FLIRT in the field

The complete system behind the twelve-digit number – including the country code and check digit – is explained in the article on the UIC number. If you want to approach identification methodically, the guide to identifying classes will help.

Why livery and operator tell you nothing about the design

Regional services are put out to tender. If another company wins a network, the operator, the livery and often the routes change too – the vehicles themselves may stay the same or be replaced entirely. Newcomers such as the Go-Ahead Group have taken over entire networks this way. For spotters, that means:

• Colour is not an identifying feature. The same vehicle type appears in many colour schemes.
• Network lists go out of date quickly. What applied last year may be obsolete after a timetable change.
• The vehicle number stays. It moves with the vehicle, even when the branding changes.
• Dated sightings are valuable. Only then can you reconstruct later which vehicle ran where and when.

That’s why every sighting should include the full vehicle number as well as the class. Where these numbers appear on the vehicle and how to read them quickly in service is covered in the article on finding train and vehicle numbers.

Photo tips for regional multiple units

Multiple units are less rewarding to photograph than locomotives: long, uniform bodysides and a flat front without much structure. Three approaches work reliably.

• Three-quarter view instead of a head-on shot. An angle of around 30 to 45 degrees shows the front and the side and makes the train’s articulation visible.
• The whole train or deliberately just the cab end. A five-car unit cut off halfway looks accidental. Decide beforehand.
• Pay attention to gangways and bogies. If you want to document the design, you need the underframe in the picture – otherwise you won’t be able to prove later that it was an articulated train.

The basics of viewpoint, shutter speed and composition are in the guide to good train photos.

Common mix-ups

The realistic risk of confusion is with the other regional multiple units of the same generation. With the Talent 2 and Talent 3, the cab end decides: the flared front cheeks are unmistakable. Double-deck multiple units are easy to tell apart anyway, because their body profile has a different height.

Why FLIRT is not a class

A common misconception with multiple units is equating the product name with the class. It regularly leads to wrong details in sightings, and it can be cleared up in a single sentence: the manufacturer assigns product names, the authority assigns class numbers.

A product name such as FLIRT, Talent, Coradia, Desiro, Mireo or KISS refers to a platform – a design family from which different vehicles can be derived: of different lengths, different speeds, with different entrance heights and types of traction. The same platform can therefore appear in several countries, with dozens of operators and under many different numbers.

The German class number, by contrast, classifies a specific batch of vehicles administratively. It tells you which number block a vehicle falls into – and, in the case of the FLIRT classes, also how many cars it has. Only the two together give the complete picture: the platform for the design, the number for the specific version.

For a clean sighting, that means: note the class and the serial number, not just the product name. “Saw a FLIRT” is about as meaningful as “saw a red train”.

Conclusion

The FLIRT is a textbook example of identifying vehicles by their design rather than their colour. Jacobs bogies, the number of cars and the cab end lead to the result in three steps, and the class number confirms it. Because contract awards regularly shuffle operators and liveries – names such as Abellio have come and gone again – this is the only approach that holds up in the long run.