a company that was originally based on the premises of a former British Leyland subsidiary Charles H Roe before moving to the new purpose-built factory in 2011 in Sherburn-in-Elmet. In 2017, Ashok Leyland acquired a further 72.31% stake in Optare increasing its overall stake to 98.31%. Technology It was the first in India to introduce multi-axled trucks, full air brakes and innovations like the rear engine and articulated buses. In 1997, the company launched the country's first CNG bus, and in 2002 developed the first hybrid electric vehicle. In the 1980s and 1990s, Ashok Leyland with various Tamil Nadu Transport Corporation, notably Cholan Roadways Corporation based in Trichripally, experimented with low pollutant emission based on the CNG technology. In 2002 it developed the first hybrid electric vehicle. Ashok Leyland has also launched a mobile emission clinic that operates on highways and at entry points to New Delhi. The clinic checks vehicles for emission levels, recommends remedies and offers tips on maintenance and care. Hythane engines Ashok Leyland has also developed hythane engines in association with the Australian company Eden Energy. Ashok Leyland developed a 6-cylinder, BS-4 engine which uses hythane (H-CNG,) which is a blend of natural gas and around 20% of hydrogen. A 4-cylinder engine is also being developed for H-CNG blend in a joint R&D program with MNRE (Ministry of New and Renewable Energy) and Indian Oil Corporation. CNG engines The CNG concept is operational, with more than 5,500 of the technology's vehicles running around Delhi. The company is also already discussing the wide-scale use of hythane engines with the Indian government. Hybrid technology Plugin Hybrid Bus In the Auto Expo 2010 at Delhi, Ashok Leyland launched India's first plug-in CNG hybrid bus, HYBUS. The hybrid bus offered 20–30% fuel saving over conventional buses powered by internal combustion engine, and were more eco-friendly than regular CNG buses, as a result of its hybrid technology that combined conventional CNG engine with electric propulsion system. The propulsion system was powered by lithium-ion battery. The other useful features of the bus included ultra-low entry at 390mm with kneeling option, noise-free rear engine, front and rear air suspensions and retractable ramp for wheel-chair entry. Some innovative pedestrian safety concepts were also introduced in the bus, like the sound and light alerts while the bus moves, a camera-assisted reversing aid for the driver and night time highlighters near the tail lights. Non-plugin Hybrid