Siemens Desiro

The Siemens Desiro is a family of diesel or electric multiple unit passenger trains designed by Siemens Mobility. The main variants are Desiro Classic, Desiro ML, Desiro UK and the later Desiro City, Desiro HC and Desiro RUS. The trains are mostly used for commuter and regional services, and the rapid acceleration makes them suitable for services within short distances between stations. The design is flexible and becomes more common in European countries.

Malaysia
The 57 km Express Rail Link line, an airport rail link service between KL Sentral railway station in central Kuala Lumpur and Kuala Lumpur International Airport to the south, uses the Desiro ET 425 M four-car Electric Multiple Units (which are technically similar to DBAG Class 425 sets in Germany). 12 trainsets are currently in operation: Eight trains are used for the non-stop KLIA Ekspres service between KL Sentral and the airport, while another four trains call at three intermediate stations in between, including one serving Putrajaya. These EMUs have a maximum commercial speed of 160 km/h making them the fastest trains currently operating in Malaysia.

United Kingdom
Siemens use the name Desiro UK for DMU and EMU operations along United Kingdom train operations. These trains are lighter compared to the Desiro Classic variant. The trainsets have modern equipment such as toilet waste retention tanks, ergonomic seats and automated information displays with spoken instructions.

EMUs
The first electric Desiro UK units were ordered by South West Trains for both short and long distance service out of London Waterloo to Alton, Basingstoke and the Hampshire/Dorset coast, to replace its Mark 1 slam door EMUs, which were due for replacement as most were more than 40 years old and did not meet modern health and safety requirements. They became two different classes, both of which use the 750 V DC third-rail power supply. One hundred and ten Class 450 four-car units for commuter services entered service in 2003, and 45 Class 444 five-car units for long-distance inter-city services entered service in 2004. An additional order for a further 17 Class 450 units was placed, with the trains in service by late 2006 and early 2007.

Former East Anglia train operator First Great Eastern acquired 21 Class 360 four-car units which operate from 25 kV overhead electrical supply for services from London Liverpool Street to Clacton-on-Sea and Ipswich. These entered service in 2003.

For the stopping service between London Paddington and Heathrow Airport called Heathrow Connect, five Class 360 five-car units were originally acquired and entered service in June 2005. However, Heathrow Express has acquired one for use on internal shuttle services.

As part of the modernisation of the West Coast Main Line, the former Strategic Rail Authority ordered 30 Class 350 dual-voltage sets for use on stopping services. They are operated by West Midlands Trains. These units were originally ordered as Class 450 third-rail units for South West Trains, but following a review by the Strategic Rail Authority they were diverted to the West Coast. The dual-voltage capability has only been used in service on temporary loan to Southern on Milton Keynes Central – East Croydon services whilst covering for a shortfall of Southern Class 377 Electrostar units. The units have been praised for their air conditioning, accessibility and performance, but criticised for their comfort (newer units have 3+2 seating). Thirty Class 350/1 four-car units entered service in 2005, and in 2008/9 a further 37 Class 350/2 four-car units entered service.

On 11 July 2008, First ScotRail ordered a number of Class 380 EMUs for delivery in 2010. The order was for 22 three-car and 16 four-car units. Entry to service began 8 December 2010. Inverclyde Line, Ayrshire Coast Line of the Class 318, Class 334 "Juniper" was introduced to replace the fleet, and the North Berwick line Class 322 trains have been replaced.

DMUs
To fulfil their franchise commitment, First TransPennine Express ordered the first diesel variant of the Desiro UK for use on its inter-city services across the north of England and over the border in southern Scotland. 51 three-car units designated as Class 185 entered service in 2006.