The British classes 220, 221 and 222 designate diesel-electric multiple units which were built by Bombardier and reach a top speed of 125 mph or 201 km/h. Independent of the length of the sets, each car has a 750 hp Cummins QSK19 providing power to the inner axle of each bogie. They became notorious when trains running over the Dawlish Seawall in south Devon during storms were stopped by software shutdowns. These were caused by the effect of salt water spaying over the roof-mounted brake resistor grids.

The class 220 is called “Voyager” and is made up of four cars. In 2000 and 2001, 34 sets were built. The main change of the class 221 “Super Voyager” is the tilting mechanism, what can be recognized by the outside-frame bogies instead of the inside-frame bogies of the 220. These 44 sets built in 2001 and 2002 can consist of four or five cars. Both classes can be run in multiple with each other.

The class 222 carries the name “Meridian”. It doesn't have a tilting mechanism and also has the inside-frame bogies seen on the 220. Between 2003 and 2005, 27 sets were built with either four or nine cars each. They were later configured to five and seven cars. Although they were already replaced by trains like the class 810 on some lines, they still have a future due to the many non-electrified lines in Britain.

In 1997, North Western Trains ordered 27 diesel multiple units from Alstom for longer distances. These class 175 trains together with the class 180 make up the “Coradia 1000” family and were built in Great Britain. The eleven two-car trains form the class 175/0 and the 16 three-car trains form the class 175/1. A part of them was originally intended to be built for 125 mph, but in the end all were only ordered for 100 mph. After being used for an extended period by Arriva Trains Wales, the operator is Transport for Wales Rail since 2021. They are to be replaced by the CAF-built class 197 in 2023.

Following the privatization of British Railways, Virgin Rail was given the InterCity West Coast franchise, which includes some lines between London and Edinburgh/Glasgow along the West Coast Main Line. Above all, the class 87 and 90 electric locomotives and the older passenger cars were to be replaced. For this purpose, a fast multiple unit was to be developed, which, thanks to tilting technology, should allow higher running speeds in cueves with a high level of passenger comfort at the same time.

The tilting technology comes from Fiat Ferroviaria and allows an inclination of up to eight degrees. In contrast to older systems, it is no longer hydraulic but electromechanical and thus saves maintenance costs. The pantographs are also tilted so that they are always in the correct position in relation to the catenary. The “Tilt Authorization and Speed Supervision” (TASS) system monitors the use of the tilting technology and the permitted speed. Trackside beacons transmit information to the train, for example to suppress tilting in narrow underpasses.

The majority of the trains' engineering comes from Fiat, but final assembly took place at Alstom's Washwood Heath facility. The trains were delivered consisting of eight cars each, but were soon expanded to include another car. The car bodies were mainly made of aluminum, with nose sections made of composite materials, which were nevertheless able to meet the crash standards of the time. A lot of work was put into the design to achieve a visually appealing, aerodynamic shape.

In seven of the nine cars, the inner axle of both bogies is powered. The traction motors are suspended under the frame and transmit their power via a cardan shaft. Although the trains are designed for 140 mph (225 km/h), they could only be approved for 125 mph (201 km/h). This is because the West Coast Main Line could not be upgraded as planned and thus the signaling does not allow for higher speeds.

Between 2001 and 2004 initially 53 sets were completed. Problems that arose caused the decommissioning of the classes 87 and 90 to be delayed. Soon the trains were setting new records on the 401 mile long WCML between London-Euston and Glasgow. The distance southbound was covered in 3 hours and 55 minutes and northbound in two minutes less. Meanwhile, on the non-electrified North Wales Coast Line, they were hauled by a class 57 diesel locomotive. A train was destroyed in a derailment at Grayrigg in 2007 where only one person died due to the structure.

From 2010, a total of 31 trains were lengthened to eleven carriages and then referred to as class 390/1. At the same time, four more were built in Italy, each consisting of eleven cars. When Avanti took over InterCity West in 2019, the Pendolinos went to Avanti West Coast. The trains are being modernized since 2021. A first-class car is exchanged for a second-class one and the interior is modernized and equipped with power sockets.

Under the name “Turbostar”, Bombardier (originally Adtranz) combined four classes of diesel multiple units that were based on the classes 165/166 “Networker Turbo”. Production took place at the Adtranz/Bombardier factory in Derby. They were the first new vehicles purchased by British railway companies after privatization, with Chiltern Railways as the first customer.

They are designed to be coupled with the “Sprinters” of classes 150 to 159. However, with a top speed of 100 mph (161 km/h), they are faster over longer distances. Compared to their predecessors, they are also largely constructed of aluminum, but have more powerful engines from MTU.

The different variants each consist of two to four cars. The first delivered Class 168 is also called “Clubman”. Classes 170 and 171 only differ in the couplers. The class 172 has bigger differences, as it has more powerful engines and a mechanical six-speed gearbox instead of the two-stage hydraulic Voith gearbox. In the subclasses 172/2 and 172/3 there are additional gangways on the fronts.

The class 350, 360 and 380 multiple units were primarily developed for use under 25 kV AC from the overhead line. The first trains in this series were 21 class 360/1 four-car trains, delivered to First Great Eastern in 2003 and handed over to Greater Anglia in 2012. They were replaced by class 720s in 2020 and 2021 and have since been used by East Midlands Railway on the Midland Main Line. In return, they've received a smaller passenger capacity and a top speed of 110 mph. The class 360/2 are similar trains that have been used by Heathrow Connect between London Paddington and Heathrow since 2004 and have been operated by TfL Rail from 2018. However, they were replaced by the Class 345 and put into storage by September 2020.

The class 350 designates four-car trains that are used on faster regional connections. The first 30 sets were created from the 120 cars that were actually intended for the class 450/2 of the South Western Railways. They can be used with 25 kV AC from the overhead line as well as with 750 V DC via the third rail and have been approved for 110 instead of 100 mph since 2012. The total number of class 350 trains was brought to 87 with the class 350/2. These can only be used in the DC network and have also been allowed to run 110 mph since 2018. Very similar to the classes 350 and 360, but only equipped for use with AC via pantographs, is the class 380. Twenty-two three-car class 380/0 trains and 16 four-car class 380/1 trains were used for the non-realised Glasgow Airport Rail Link ordered and delivered between 2009 and 2011. They have a new, futuristic design at the front and are provided with gangways. These are now used by Abellio ScotRail on other routes in Scotland.