First Bus Upgrades 220 Buses With Allison’s xFE Transmission

Allison’s transmissions reduce fuel consumption by 8.5%, paying back the cost of the upgrade in little more than a year and prolonging the operational life of the bus.

AMPTHILL, United Kingdom, November 2021 – Allison Transmission, a leading designer and manufacturer of conventional and electrified vehicle propulsion solutions and the largest global manufacturer of medium- and heavy-duty fully automatic transmissions for commercial and defense vehicles, will supply 220 T2100 xFE™ transmissions to First Bus, one of the largest bus operators in the United Kingdom (UK).

The order is for the retrofitting of all ADL Enviro 200, Optare Solo and Optare Versa buses within the First Bus fleet that are currently equipped with Allison’s T2100 transmission. It follows trials, which showed improved fuel consumption by 8.5% when upgraded with xFE Technology. Savings made on diesel bills are expected to pay back the investment in the new transmissions in less than 13 months.

First Bus conducted its xFE study across the UK throughout 2020 on nine ADL Enviro 200 buses and one Optare Solo. Most of these vehicles were 12 years old and were fitted with xFE at the point of their final routine transmission replacement. Fuel consumption was compared with buses of the same type and took into account factors such as duty cycles, traffic conditions, route topographies and vehicle life stage.

“As part of our focus on becoming a leader in the transition to a low-carbon future for public transportation, First Bus has committed to ceasing the purchase of any new diesel buses after 2022,” said Peter Mambara, Technical Manager at FirstGroup. “However, we recognised xFE as a stepping-stone technology on the path to full electrification. We had seen stories of other fleets achieving 7-8% fuel savings from xFE in urban driving conditions, but wanted to independently assess the savings on buses that also serve on rural routes. The 8.5% improvement was convincing evidence that the upgrade will help reduce our fleet’s CO2 emissions and make good financial sense.”

“As the xFE transmission has demonstrated with First Bus, in addition to other trials Allison has undertaken globally, there is a lot that can be done to make the current generation of diesel engines cleaner. Even towards the end of a vehicle’s life, there is both an immediate environmental and short term business case to be made for upgrading to the latest fuel saving transmission technology,” said Jade Noble, Allison Transmission OEM Account Manager and Area Sales Manager, UK and Ireland.

First Bus will install the xFE upgrades over the next 18 months when last-life transmission replacements are due on 142 Enviro 200s, 60 Optare Solos, and 18 Optare Versas. Though such buses typically remain in service for 15 years, with transmissions routinely replaced every two to three years, these vehicles could now remain in service for two years longer than previously anticipated because xFE has a longer lifespan than comparable heavy-duty transmissions. The exceptional durability of the xFE transmission is affirmed by Allison offering it with a standard two-year warranty package and the option to extend at additional cost for a further five years.

Allison’s latest fully automatic transmission for buses delivers extra fuel efficiency by optimizing gear ratios which enable torque converter lock-up in first gear and operation at lower engine speeds in higher ranges. This strategy is ideally suited to city and transit buses.

Nov 11, 2021


Allison Transmission (NYSE: ALSN) is a leading designer and manufacturer of vehicle propulsion solutions for commercial and defense vehicles, the largest global manufacturer of medium- and heavy-duty fully automatic transmissions, and a leader in electrified propulsion systems that Improve the Way the World Works. Allison products are used in a wide variety of applications, including on-highway trucks (distribution, refuse, construction, fire and emergency), buses (school, transit and coach), motorhomes, off-highway vehicles and equipment (energy, mining and construction applications) and defense vehicles (tactical wheeled and tracked). Founded in 1915, the company is headquartered in Indianapolis, Indiana, USA. With a presence in more than 150 countries, Allison has regional headquarters in the Netherlands, China and Brazil, manufacturing facilities in the USA, Hungary and India, as well as global engineering resources, including electrification engineering centers in Indianapolis, Indiana, Auburn Hills, Michigan and London in the United Kingdom. Allison also has more than 1,400 independent distributor and dealer locations worldwide. For more information, visit